IMS Simple Sequencing Information and Behavior Model Version 1.0 Final Specification

Copyright © 2003 IMS Global Learning Consortium, Inc. All Rights Reserved.
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Document Name: IMS Simple Sequencing Information and Behavior Model
Revision: 03 March 2003 

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Table of Contents

I.   Introduction

I.1   Overview

This document, the "IMS Simple Sequencing Specification," defines a method for representing the intended behavior of an authored learning experience such that any learning technology system (LTS) can sequence discrete learning activities in a consistent way. A learning designer or content developer declares the relative order in which elements of content are to be presented to the learner and the conditions under which a piece of content is selected, delivered, or skipped during presentation.

This specification defines the required behaviors and functionality that conforming systems must implement. It incorporates rules that describe the branching or flow of learning activities through content according to the outcomes of a learner's interactions with content. This representation of intended instructional flow may be created manually or with authoring systems that produce output that conforms to this specification. While learning content developers need to know how to create and describe content sequences, authoring systems may hide the details of the models presented in this specification. The representation of sequencing may be interchanged between systems designed to deliver instructional activities to learners. The components of an LTS used to execute the specified rules and behaviors, when content is delivered to a learner, are referred to in this specification as a 'sequencing engine'.

Simple Sequencing is labeled as simple because it includes a limited number of widely used sequencing behaviors, not because the specification itself is simple. Simple Sequencing is not all-inclusive. In particular, Simple Sequencing does not address, but does not necessarily preclude, artificial intelligence-based sequencing, schedule-based sequencing, sequencing requiring data from closed external systems and services (e.g., sequencing of embedded simulations), collaborative learning, customized learning, or synchronization between multiple parallel learning activities.

Simple Sequencing recognizes only the role of the learner and does not define sequencing capabilities that utilize or are dependent on other actors, such as instructors, mentors, or peers. This specification does not prohibit usage in contexts involving other actors; however, it does not define the roles of other actors or sequencing behaviors that result from participation of other actors.

Simple Sequencing enables digital content to be rendered and presented to a learner in a Web-based environment; however, it is not restricted to a Web-based environment. The nature of the control and communication interfaces, and the mechanisms for mediating interactions between a learner and a LTS, are not part of this specification. In addition, issues such as look and feel, presentation style, and placement of navigation controls are not defined by this specification.

Simple Sequencing provides an external representation, via extensions to the "IMS Content Packaging XML Binding" [3]1, to exchange sequencing descriptions between different runtime components or LTSs. Although the Simple Sequencing Specification is based on the same content organization and tree structure as the Content Packaging Specification, Simple Sequencing does not require Content Packaging. However, Content Packaging is currently the only defined mechanism for exchanging definition model instances.

I.2   IMS Simple Sequencing Components

Simple Sequencing is described in the following set of interrelated documents:

• Simple Sequencing Information and Behavior Model (this document) - This document is the normative reference that defines the behavior and an Information Model consisting of a Sequencing Definition Model, a Tracking Model, and an Activity State Model. It is written for implementers of sequencing services and authoring tools.
• XML Binding [4] - This document describes how the Sequencing Definition Model is represented as extensions to the organization component of the manifest of the XML binding of the IMS Content Packaging Specification.
• Best Practice and Implementation Guide [5] - This document describes implementation considerations for those implementing the behaviors described in this specification.

I.3   Simple Sequencing Specification Sections

This specification defines a small subset of all possible sequencing operations and the informational elements required to describe the desired operations and their parameters. To enable interoperability, systems that deliver learning content must be able to interpret the sequencing information and exhibit the behaviors defined in this specification. This presentation is divided into several sections, each section being standalone and describing one part of the Simple Sequencing Specification.

• Sequencing Definition Model - The information model in Simple Sequencing used to describe the desired sequencing behavior (see part SM).
• Tracking Model - The information model in Simple Sequencing used to record information about the results of a learner's interactions with activities, and the learner's record for objectives (e.g., completion, measure) to control the selection and sequencing of other activities (see part TM).
• Activity State Model - The information model in Simple Sequencing used to record information about the state or status of a learner's interactions with an activity and a set of global attributes for activities (see part AM).
• Overall Sequencing Process - The overall Simple Sequencing process that relates the selection and randomization, navigation, sequencing, exit, rollup and delivery processes (see part OP).
• Navigation Behavior Model - The Simple Sequencing process that evaluates a navigation request and determines the sequencing and termination requests that should be processed to identify and deliver content to the learner (see part NB).
• Termination Behavior Model - The Simple Sequencing process that evaluates a termination request to end an attempt on an activity (see part TB).
• Rollup Behavior Model - The Simple Sequencing process that computes the results data for an activity from the results data from the children of the activity (see part RB).
• Selection and Randomization Behavior Model - The Simple Sequencing process that selects and reorders a subset of activities (see part SR).
• Sequencing Behavior Model - The Simple Sequencing process that evaluates a sequencing request in terms of the content model described by the activity tree and determines what actual content object should be delivered to the learner (see part SB).
• Delivery Behavior Model - The Simple Sequencing process that validates that the learning resources for the identified activity may be delivered, i.e., all of the conditions that apply to the delivery of the content for the activity and attempt still hold (see part DB).
• Utility Processes - Sequencing processes that are utilized by multiple behavioral models (see part UP).
• Extensibility - The extensibility mechanisms in Simple Sequencing (see part E).
• Conformance - Requirements on an implementation to conform to the Simple Sequencing Specification (see part C).
• Glossary - A collection of terms used throughout the Simple Sequencing document set to describe parts of the information models of sequencing behaviors specific to this description of Simple Sequencing (see part G).
• Use Cases - A collection of sample sequencing cases used throughout the Simple Sequencing development process to guide the selection of features and functions (see part UC).

Section	Mnemonic
Introduction	I
Sequencing Definition Model	SM
Tracking Model	TM
Activity State Model	AM
Overall Sequencing Process	OP
Navigation Behavior Model	NB
Termination Behavior Model	TB
Rollup Behavior Model	RB
Selection and Randomization Behavior Model	SR
Sequencing Behavior Model	SB
Delivery Behavior Model	DB
Utility Processes	UP
Extensibility	E
Conformance	C
Glossary	G
Use Cases	UC

The sections are intentionally independent so that an implementer or reader has all the information related to the topic and other key information needed to interpret and implement the corresponding part of a Simple Sequencing system. Each section may include:

• Information Model - The detailed description of the corresponding information model (the Sequencing Definition Model, the Tracking Model, and the Activity State Model). Each information model is divided into logically related sets of data attributes. Each set describes the data items in a binding-independent fashion.
• Behavior - The detailed description of the behaviors and procedures that describe the parts of Simple Sequencing (for each of the behavior models). Each behavior includes one or more process descriptions in pseudo code.

I.4   Assumptions

I.4.1   Activity Tree

The Simple Sequencing Specification relies on the concept of learning activities. A learning activity may be loosely described as an instructional event or events embedded in a content resource, or as an aggregation of activities that eventually resolve to discrete content resources with their contained instructional events.

Content in Simple Sequencing is organized into a hierarchical structure. Each activity may include one or more child activities. Each activity has an associated set of sequencing behaviors, defined by the sequencing definition model (see Sequencing Definition Model SM). The sequencing behaviors describe how the activity or how the children of the activity are used to create the desired learning experience.

The sequencing behavior process (see Sequencing Behavior Model SB) traverses the activity tree, applying the sequencing rules, to determine the activities to deliver to the learner. Content resources from the identified activities are delivered to the learner to create the desired learning experience.

Simple Sequencing makes no requirements on the structure, organization, or instantiation of the activity tree. The tree and the associated sequencing definitions may be static or they may be dynamically created. How to create, represent, and maintain the activity tree and associated sequencing definition is not specified.

I.4.2   Sequencing Loop

The following sequencing loop describes how the various behavior processes interact during sequencing and delivery. The description assumes the activity tree exists and has been initialized.

Begin Sequencing Session

1. The learner initiates access to the content delivery environment or LTS (e.g., accesses the system, logs in) and establishes a context within a particular unit of instruction (e.g., selects a course or content aggregation).
2. The LTS initiates a sequencing session by issuing a "Start", "Resume All", or "Choice" navigation request.
3. The navigation behavior translates the "Start", "Resume All", or "Choice" navigation request into the corresponding sequencing request and processes it. The sequencing session 'officially' begins when an activity is identified for delivery (successful completion of steps 4 and 5).

Start of Sequencing Loop

4. Using the information in the tracking model and the sequencing request, the sequencing behavior traverses the activity tree attempting to identify the appropriate activity (node in the tree) to deliver to the learner.
5. The delivery behavior determines if the identified activity can be delivered, and if so, prepares to deliver the activity's content resource(s) to the learner. If the selected activity cannot be delivered, then the overall sequencing process stops and waits for another navigation request (step 8).
6. The learner interacts with the content resource. The sequencing processes are idle and waiting for requests while the learner interacts with the content resource.
7. The activity may report values that update the various tracking model elements during the learner's interactions with the content resource.
8. The learner, delivery system, or activity invokes a navigation event, such as "Continue", "Previous", "Choose activity X", "Abandon", "Exit", etc...
9. The LTS informs the sequencing process of the navigation event by issuing a navigation request.
10. The navigation behavior translates the navigation request into a termination request and a sequencing request. If the navigation request indicates that the learner wants to end the sequencing session, the sequencing session ends (the behavior of ending the sequencing session and the persistence of the activity state model is unspecified and left to the implementation).
11. If the activity triggered the navigation request by terminating or exiting, it may report additional values that update the tracking model. The activity then exits. The rollup process is invoked to determine the effects of any state changes that occurred as a result of delivering the content resource for the activity. The process updates the tracking model for the activity and for any of its parent activities within the activity tree.
12. The process repeats beginning at step 4, until the sequencing session ends.

Several variations exist on the order described above, including:

• Selection and randomization of activities may occur prior to the processing of a sequencing request.
• An activity may report state and status information and exit without triggering a specific navigation request.
• Only certain classes of resources and activities may report information to the tracking model during delivery of content and learner interaction with the content.

The sequencing process may not be able to identify an activity to deliver, or the activity may not be delivered due to failure to meet the defined delivery conditions.

Figure I.1 above shows the various steps in the sequencing process. The control process is shown on the left. In normal operation, the overall sequencing process flows from navigation behavior to termination behavior to sequencing behavior to delivery behavior, followed by a wait while the learner interacts with the content resource, as described in steps 4-12 above.

The right side of Figure I.1 shows the learner's view of the learning experience. A content resource is delivered to the learner. The learner interacts with the content resource and results may be returned to the tracking model. The learner triggers an event that maps to a navigation request. The navigation request triggers the various steps in the sequencing process.

Throughout all sequencing processes, a collection of state and tracking model data is maintained. Content resources may directly set values in the tracking model through a runtime communications interface to tracking model; this interface is not part of the specification and is not required. All of the other sequencing processes access and update elements of the tracking models.

Changes to the state of an activity occur because of learner interaction with a content resource delivered for the activity or one of its descendents. If an external event affects the tracking, such as an instructor changing a grade, the model assumes processes are invoked as required to update the activity state model.

Changes to the activity state model and tracking model that occur outside of the scope of delivering the learning experience via the sequencing process are outside of the scope of the specification. Systems that implement such side effects and additional capabilities must deal with these conditions accordingly.

I.4.3   Rule-Based Model

The behaviors described in the Simple Sequencing Specification are defined in terms of sequencing information (see Sequencing Definition Model SM) associated with activities in the activity tree. Sequencing information includes 'rules' that provide a means to describe conditional sequencing behavior at content development time. These 'rules' and tracking status information affect the various sequencing processes during content delivery.

I.4.4   Default and Authored Behavior

In the absence of explicitly defined sequencing information, activity trees exhibit default sequencing behaviors when content resources are delivered. These default behaviors and associated values are specified in the sequencing information (see Sequencing Definition Model SM). Content developers may change default behaviors by explicitly defining sequencing information and associating it with activities.

I.4.5   Objectives

Learning objectives are separate from activities in Simple Sequencing. Learning objectives represent a set of locally and globally scoped data items, each with a satisfaction status and a satisfaction measure. Simple Sequencing makes no assumption as to how to interpret the objective (e.g., is it a competency, is it a mastery, or is it simply a shared value?). Activities may have more than one associated local objective and may reference multiple globally shared objectives. Multiple activities may reference the same global objective, thus sharing the data values.

The resolution of local and global objective IDs is not specified. An objective may be shared within a single activity tree or may be shared globally across multiple instantiations of tracking models. The lifetime of shared global objectives and the scope of sharing is not specified; it is determined by implementations. Activities may reference multiple objectives, thus providing a mechanism for activities to have sub-objectives. However, this specification makes no assumptions about the semantics or meanings of multiple objectives associated with an activity.

I.4.6   Auxiliary Resources

An activity may have auxiliary resources associated with it that provide additional services or resources for the learner. This specification does not define any semantics or meanings for these auxiliary resources. This specification does not define which resources may be made available, or how the resources are to be used; it only provides a means for the auxiliary resources to be associated with an activity.

I.4.7   Presentation and Environment

Simple Sequencing makes no assumption as to how content and controls are rendered or presented to the learner (e.g., style, placement, GUI widgets). How events are triggered in the interface environment, how they are communicated to the LTS, and how the LTS delivers content to the learner and the learner's environment are not specified.

While an external event may trigger a navigation event and a resulting navigation request, the external event also may trigger other actions. These behaviors are not specified.

I.4.8   Suspending and Resuming Activities

An activity may be suspended and later resumed. Certain navigation requests result in an activity or collection of activities being suspended. Other activities may be delivered while the activity is suspended. A suspended activity may be resumed later without counting as a new activity attempt. Additionally, the suspended activity may be abandoned or exited.

The current sequencing session may be suspended and later resumed at the last activity experienced by the learner.

I.4.9   Starting and Stopping the Sequencing Process

Simple Sequencing does not specify how to start the overall sequencing process or how to stop the process. Generally, the LTS will recognize some event, e.g., a course login, to start sequencing. Some other event, e.g., a logout, is mapped to the appropriate navigation, exit and sequencing requests, after which the LTS may terminate the overall sequencing process.

I.4.10   Data Persistence

Simple Sequencing does not specify how data (e.g., tracking data) is to be persisted across multiple instantiations of the overall sequencing process for a particular learner and activity tree or learning experience, e.g., across multiple login sessions. Implementations shall persist control, tracking, and state data at least until the current attempt on the activity tree is terminated. Such an attempt may include one or more login sessions. LTS policies govern whether to persist data beyond that time; such policies are beyond the scope of this specification.

I.4.11   Content Types

The Simple Sequencing Specification is independent of the types of learning content and learning objects and can be used to sequence all types of content. For example, content may include simple static Seb pages, MIME resources of any type (e.g., DOC, PDF files), services and proxies for services, and dynamically created objects. In particular, content need not use a communications adapter, such as the AICC/IEEE/ADL SCORM API communications adapter used by sharable content objects [2]. Nor does Simple Sequencing require a runtime service or assume the existence of other data models, such as the CMI data model [1].

I.4.12   Active/Passive Content

Simple Sequencing relies on values within the tracking model to control sequencing. Simple Sequencing does not specify how the tracking model values for an activity or an objective are set or updated. Simple Sequencing differentiates between active and passive content and supports both active and passive content on an activity-by-activity basis. Active content is responsible for setting elements of the tracking model directly. For passive content, Simple Sequencing will automatically set certain values in the tracking model. Simple Sequencing makes no assumptions about how content actually behaves, e.g., passive content may set values in the tracking model, active content may fail to set values Simple Sequencing relies only on the declaration of how the content should behave.

I.4.13   Relationship to IMS Content Packaging Specification

The Simple Sequencing Specification relies on the concept of learning activities. A learning activity may be loosely described as an instructional event or events embedded in a content resource, or as an aggregation of activities that eventually resolve to discrete content resources with their contained instructional events.

The IMS Content Packaging Specification provides a ready structure for relating a learning activity to a content resource - the item element and its relationship to a resource element. Furthermore, item elements can be clustered into collections, with such collections contained in a parent organization element, just like learning activities may clustered together in a parent activity or activities. Therefore, Simple Sequencing maps the concept of a learning activity to an item element or a collection of item elements within an organization element, and to an organization element itself, as defined by the Content Packaging Specification. The Content Packaging XML Binding is extended by this specification to define how sequencing information is associated with packaged content.

The process of defining a specific sequence of learning activities begins with the creation of an aggregation of content. The Content Packaging Specification enables aggregations to be interchanged among systems. As shown in the figure below, the content packaging organization element and each item element within it can have defined sequencing behaviors through the association of sequencing information defined in the sequencing definition Model (see Sequencing Definition Model SM). Sets of sequencing definition elements can be created and defined for or referenced by items within the organization, as well as for the organization itself. A single set of sequencing definition elements and values can be referenced by more than one item and therefore are reusable.

All information defining sequencing behavior for an organization is present within that organization. Where multiple organizations are present within a manifest, each organization may have its own set of sequencing behaviors.

IMS Simple Sequencing only describes how sequencing information relates to IMS Content Packaging, but does not prohibit sequencing information and behavior from being used in other contexts.

This version of Simple Sequencing does not use or prohibit the use of sub manifests, defined in IMS Content Packaging.

I.5   Nomenclature

The following abbreviations and acronyms are used in this document:

ADL	Advanced Distributed Learning
AICC	Aviation Industry CBT Committee
ANSI	American National Standards Institute
API	Application Programming Interface
CBT	Computer Based Training
CMI	Computer Managed Instruction
CPI	Content Packaging Interchange
DTD	Document Type Definition
IEEE	Institute of Electronic and Electrical Engineering
ISO	International Standards Organization
JTC	Joint Technical Committee
LTS	Learning Technology System
LTSC	Learning Technology Standards Committee
SCORM	Shareable Content Object Reference Model
SS	Simple Sequencing
W3C	World Wide Web Consortium
XML	Extensible Mark-up Language

I.6   References

[1]	IEEE P1484.11.1 Draft Standard for Data Model to Content Object Communication
[2]	IEEE P1484.11.2 Draft Standard for ECMAScript API for Content to Runtime Services Communication
[3]	IMS Content Packaging XML Binding v1.1.2 Final Specification, IMS Global Learning Consortium, Inc., August 2001
[4]	IMS Persistent, Location-Independent Resource Identifier Handbook v1.0, Final Specification, IMS Global Learning Consortium, Inc., April 2001
[5]	IMS Simple Sequencing XML Binding v1.0 Final Specification, IMS Global Learning Consortium, Inc., March 2003
[6]	IMS Simple Sequencing Best Practice and Implementation Guide v1.0 Specification, IMS Global Learning Consortium, Inc., March 2003

SM.   Sequencing Definition Model

The Simple Sequencing process uses information about the desired sequencing behavior to control the sequencing, selection and delivery of activities to the learner. The intended sequence is described by a specific set of data attributes. These attributes are associated with learning activities in the activity tree to describe the sequencing behavior. The set of attributes used by Simple Sequencing is called the "sequencing definition model".

The sequencing definition model consists of:

• Sequencing Control Modes - controls for types of sequencing requests that may apply to a collection of activities.
• Sequencing Rule Description - rules applied to an activity used to specify sequencing behaviors for the activity.
• Limit Conditions Description - limits on how many times, how long and when an activity is allowed.
• Rollup Rule Description - rules that specify how tracking data from an activity or its associated objectives is produced from the results of the child activities.
• Objective Description - the learning objectives associated with an activity.
• Objective Map - the mapping of local objective information to and from shared global objectives.
• Rollup Controls - controls which data from an activity contributes to the rollup of the parent activity.
• Selection Controls - controls how an activity's children are selected.
• Randomization Controls - controls how an activity's children are ordered.
• Delivery Controls - controls when progress and objective information for an activity are recorded.

There are no overall behavior requirements on the use and instantiation of the sequencing definition model. Individual parts of the model describe how the sequencing definitions are associated with the activity tree to define intended learning experiences. The use of the sequencing definition model is detailed as part of the behavior descriptions of the navigation, sequencing, delivery, exit, selection, randomization, and rollup processes.

Sequencing definitions describe the intended learning experience for a learner. How the learning experience and definition for a learner relate to the definition for a cohort of learners (e.g., individualized experiences versus a common experience for all members of the cohort) is not specified. A sequencing definition model instance defines a learning experience independently of how it is instantiated for one or more learners.

SM.1   Sequencing Control Modes

Sequencing control mode information (the set of attributes shown below) includes descriptions of the types of sequencing behaviors specified for an activity. Sequencing control mode information for an activity includes the associated data listed below.

Simple Sequencing processes may reference the sequencing control modes for any activity in the activity tree. Sequencing control modes are optional. Default data is used if the data is not defined for a given activity.

The control modes are not exclusive; multiple control modes may be specified.

No.	Name	Description	Value Space	Default Value
1	Sequencing Control Choice	Indicates that a Choice sequencing request is permitted (True or False) to target the children of the activity.	Boolean	True
2	Sequencing Control Choice Exit	Indicates that an active child of this activity is permitted to terminate (True or False) if a Choice sequencing request is processed.	Boolean	True
3	Sequencing Control Flow	Indicates the Flow Subprocess (SB.2.3) may be applied (True or False) to the children of this activity.	Boolean	False
4	Sequencing Control Forward Only	Indicates that backward targets (in terms of activity tree traversal) are not permitted (True or False) for the children of this activity.	Boolean	False
5	Use Current Attempt Objective Information	Indicates that the objective progress information (TM.1.1) for the children of the activity will only be used (True or False) in rule evaluations and rollup if that information was recorded during the current attempt on the activity.	Boolean	True
6	Use Current Attempt Progress Information	Indicates that the attempt progress information (TM.1.2.2) for the children of the activity will only be used (True or False) in rule evaluations and rollup if that information was recorded during the current attempt on the activity.	Boolean	True

SM.2   Sequencing Rule Description

Sequencing rule description (the set of attributes shown below) specifies the details of individual rule-based sequencing behaviors for an activity. Sequencing rule description information for an activity includes the associated data listed below.

Simple Sequencing processes may reference the sequencing rules for any activity in the activity tree. Sequencing rules are optional. The data attributes below specify one rule. Each activity may have an unlimited number of sequencing rules. Sequencing rules are defined only where needed. Default data is used if the data is not instantiated for a given rule, if needed.

• The data attributes below describe one rule. Each activity may have an unlimited number of sequencing rules.
• The general format of a rule can be expressed informally as: If condition set Then action.
• There may be multiple conditions.
• The conditions may be combined with a single and combination (all conditions must be True) or a single or combination (only one condition must be True).
• Individual condition values may be negated before being combined in the rule evaluation.
• No other operators on the conditions are defined.
• Each condition references an item in the tracking model for the activity or one of its associated objectives.
• There is one action that may result if the rule conditions evaluate to True.

Actions are divided into three groups:

• Preconditions - Actions that control sequencing decisions and delivery of a specific activity. Rules that include such actions are used to determine if the activity will be delivered.
• Post Conditions - Actions that control sequencing flow by issuing sequencing requests. Rules that include such actions are applied when an activity terminates.
• Exit Actions - Actions that terminate an activity. Rules that include such actions are applied when a descendent of an activity exits.

The Rule Conditions, Condition Combination, and Rule Actions are tokens in a vocabulary. The tokens have no semantics or meanings themselves. The description of the condition or action is the complete definition of the required behavior.

No.	Name	Description	Value Space	Default Value
1	Condition Combination	How rule conditions are combined in evaluating the rule. All - The rule condition evaluates to True if and only if all of the individual rule conditions evaluate to True (logical and). Any - The rule condition evaluations to True if and only if any of the individual rule conditions evaluates to True (logical or).	Vocabulary	All
2	Rule Conditions	An unordered collection of conditions for a sequencing rule. A rule may include multiple rule conditions.	Collection 0:N
2.1	Rule Condition	A condition element for the rule. Satisfied - evaluates to True if the Objective Progress Status (TM.1.1) for the objective associated with the activity (indicated by Rule Condition Referenced Objective) is True and the Objective Satisfied Status (TM.1.1) for the objective associated with the activity (indicated by Rule Condition Referenced Objective) is True. Objective Status Known - evaluates to True if the Objective Progress Status (TM.1.1) for the objective associated with the activity (indicated by Rule Condition Referenced Objective) is True. Objective Measure Known - evaluates to True if the Objective Progress Status for the objective (TM.1.1) associated with the activity (indicated by Rule Condition Referenced Objective) is True and the Objective Measure Status (TM.1.1) for the objective associated with the activity (indicated by Rule Condition Referenced Objective) is True. Objective Measure Greater Than - evaluates to True if the Objective Measure Status (TM.1.1) for the objective associated with the activity (indicated by Rule Condition Referenced Objective) is True and the Objective Normalized Measure (TM.1.1) for the objective associated with the activity (indicated by Rule Condition Referenced Objective) is greater than the Rule Condition Measure Threshold. Objective Measure Less Than - evaluates to True if the Objective Measure Status (TM.1.1) for the objective associated with the activity (indicated by Rule Condition Referenced Objective) is True and the Objective Normalized Measure (TM.1.1) for the objective associated with the activity (indicated by Rule Condition Referenced Objective) is less than the Rule Condition Measure Threshold. Completed - evaluates to True if the Attempt Progress Status (TM.1.2.2) for the activity is True and the Attempt Completion Status (TM.1.2.2) for the activity is True. Activity Progress Known - evaluates to True if the Activity Progress Status (TM.1.2.1) for the activity is True and the Attempt Progress Status (TM.1.2.2) for the activity is True. Attempted - evaluates to True if the Activity Progress Status (TM.1.2.1) for the activity is True and the Activity Attempt Count (TM.1.2.1) for the activity is positive (i.e., the activity has been attempted). Attempt Limit Exceeded - evaluates to True if the Activity Progress Status (TM.1.2.1) for the activity is True and the Limit Condition Attempt Limit Control (SM.3) for the activity is True and the Activity Attempt Count (TM.1.2.1) for the activity is equal to or greater than the Limit Condition Attempt Limit (SM.3) for the activity. Time Limit Exceeded - evaluates to True if the Activity Progress Status (TM.1.2.1) for the activity is True and any of the durations for the activity (Activity Absolute Duration, Activity Experienced Duration, Attempt Absolute Duration, Attempt Experienced Duration) exceed the corresponding duration Limit Condition values for the activity (SM.3 - Limit Condition Activity Absolute Duration, Limit Condition Activity Experienced Duration, Limit Condition Attempt Absolute Duration, Limit Condition Attempt Experienced Duration) and the associated Limit Condition control value (SM.3 - Limit Condition Activity Absolute Duration Control, Limit Condition Activity Experienced Duration Control, Limit Condition Attempt Absolute Duration Control, Limit Condition Attempt Experienced Duration Control) for the activity is True. Outside Available Time Range - evaluates to True if the current time is before or after the corresponding time Limit Condition values for the activity (SM.3 - Limit Condition Begin Time, Limit Condition End Time) and the associated Limit Condition control value (SM.3 - Limit Condition Begin Time Control, Limit Condition End Time Control) for the activity is True. Always - always evaluates to True.	Vocabulary	Always
2.2	Rule Condition Referenced Objective	The identifier of an objective associated with the activity used during the evaluation of the condition. If a rule for an activity does not explicitly reference an objective by an identifier, the rule references the objective that contributes to rollup for an activity by default.	Unique Identifier1	None
2.3	Rule Condition Measure Threshold	The value used as a threshold during measure-based condition evaluations.	Real [-1..1] Precision of at least 4 significant decimal digits	0.0
2.4	Rule Condition Operator	The unary logical operator to be applied to the condition. Not - The corresponding condition is negated in rule evaluation. NO-OP - The corresponding condition is used as is in rule evaluation.	Vocabulary	NO-OP
3	Rule Action	The desired sequencing behavior if the rule evaluates to True. Actions are divided into groups based on when the action is applied. Precondition actions apply when traversing the activity tree to identify an activity for delivery: Skip - The activity is not considered a candidate for delivery during a Flow sequencing process (SB.2.3). Disabled - The activity may not be the target of any sequencing or delivery request. Hidden from Choice - The activity may not be the target of a Choice sequencing request. Stop Forward Traversal - Stop walking the activity tree, in a forward direction, at the activity while processing a sequencing request. Ignore - No action. Post Condition actions apply when an attempt on the activity terminates: Exit Parent - Process an Exit Parent exit request. Exit All - Process an Exit All termination request and return an Exit sequencing request. Retry - Return a Retry sequencing request. Retry All - Process an Exit All termination request and return a Start sequencing request. Continue - Return a Continue sequencing request. Previous - Return a Previous sequencing request. Ignore - No action. Exit actions apply after an attempt on a descendent activity terminates: Exit - Unconditionally terminate the activity. Ignore - No action.	Vocabulary	Ignore

1 This identifier should be globally unique, or at least unique in any scope in which sequenced activities might be used. The IMS Persistent, Location-Independent Resource Identifier Handbook [4] describes the recommended way to construct such an identifier.

SM.3   Limit Conditions Description

Limit conditions description (the set of attributes shown below) define constraints on the access to an activity based on time of day, time spent on the activity and number of attempts. Limit conditions description for an activity includes the associated data listed below.

Simple Sequencing processes may reference the limit conditions description for any activity in the activity tree. Limit Conditions are optional. Limit condition data need not be defined for each activity in the activity tree. Default data is used if the data is not instantiated for the activity, if needed.

No.	Name	Description	Value Space	Default Value
1	Limit Condition Attempt Control	Indicates that a limit condition on the number of attempts for the activity has been established (True or False) for the activity. If the value is False, there is no constraint on how many times the activity may be attempted.	Boolean	False
2	Limit Condition Attempt Limit	The maximum number of attempts for the activity. A zero value indicates the activity may not be accessed. The value is unreliable unless Limit Condition Attempt Control is True.	Non Negative Integer	0
3	Limit Condition Attempt Absolute Duration Control	Indicates that a limit condition on the maximum time duration that a learner is permitted to spend on any single attempt on the activity has been established (True or False) for the activity. If the value is False, there is no constraint on how long the learner may spend on the activity.	Boolean	False
4	Limit Condition Attempt Absolute Duration Limit	The maximum time duration that a learner is permitted to spend on any single attempt on the activity. This limit applies to the time the activity is active - from the time the activity begins until the time the activity ends, including any time the activity was suspended. A zero value indicates the activity may not be accessed. The value is unreliable unless Limit Condition Attempt Absolute Duration Control is True.	Duration Accuracy 0.1 second	0.0
5	Limit Condition Attempt Experienced Duration Control	Indicates that a limit condition on the maximum time duration that a learner is permitted to spend on any single attempt on the activity has been established (True or False) for the activity. If the value is False, there is no constraint on how long the learner may spend on the activity.	Boolean	False
6	Limit Condition Attempt Experienced Duration Limit	The maximum time duration that a learner is permitted to spend experiencing a single attempt on the activity. The limit applies to only the time the learner is actually interacting with the activity and does not apply when the activity is suspended (i.e., when the activity is not being experienced or is inactive). A zero value indicates the activity may not be accessed. The value is unreliable unless Limit Condition Attempt Experienced Duration Control is True.	Duration Accuracy 0.1 second	0.0
7	Limit Condition Activity Absolute Duration Control	Indicates that a limit condition on the maximum duration that a learner is permitted to spend on the activity (which includes all attempts) has been established (True or False) for the activity. If the value is False, there is no constraint on how long the learner may spend on the activity.	Boolean	False
8	Limit Condition Activity Absolute Duration Limit	The maximum time duration that a learner is permitted to spend on all attempts at the activity. A zero value indicates the activity may not be accessed. The value is unreliable unless Limit Condition Activity Absolute Duration Control is True.	Duration Accuracy 0.1 second	0.0
9	Limit Condition Activity Experienced Duration Control	Indicates that a limit condition on the maximum duration that a learner is permitted to spend on the activity (which includes all attempts) has been established (True or False) for the activity. If the value is False, there is no constraint on how long the learner may spend on the activity.	Boolean	False
10	Limit Condition Activity Experienced Duration Limit	The maximum time duration that a learner is permitted to spend on all attempts of the activity. The limit applies to only the time the learner is actually experiencing the activity and does not apply when the activity is suspended (i.e., when the activity is not being experienced or is inactive). A zero value indicates the activity may not be accessed. The value is unreliable unless Limit Condition Activity Experienced Duration Control is True.	Duration Accuracy 0.1 second	0.0
11	Limit Condition Begin Time Limit Control	Indicates that a limit condition on the availability of the activity has been established (True or False) for the activity. If the value is False, there is no constraint on when the learner may access the activity.	Boolean	False
12	Limit Condition Begin Time Limit	The date and time before which the activity is not available. The value is unreliable unless Limit Condition Begin Time Limit Control is True.	Time Point Accuracy 0.1 second	October, 15 1582 00:00:00.0
13	Limit Condition End Time Limit Control	Indicates that a limit condition on the availability of the activity has been established (True or False) for the activity. If the value is False, there is no constraint on when the learner may access the activity.	Boolean	False
14	Limit Condition End Time Limit	The date and time after which the activity is not available. The value is unreliable unless Limit Condition End Time Limit Control is True.	Timepoint Accuracy 0.1 second	October, 15 1582 00:00:00.0

SM.4   Auxiliary Resource Description

Auxiliary resource description (the set of attributes shown below) defines an auxiliary resource associated with an activity. When an activity is delivered to the learner, the auxiliary resources are also made available to the learner. An auxiliary resource description for an activity includes the associated data listed below.

Simple Sequencing processes may reference the auxiliary resource description for any activity in the activity tree. Auxiliary resources are optional. Auxiliary resource data need not be defined for each activity in the activity tree. If an auxiliary resource is instantiated for an activity, it must provide the required data.

The data attributes below describe one auxiliary resource. Each activity may have an unlimited number of unordered auxiliary resources.

Purpose is an open, unspecified vocabulary. The vocabulary tokens have no semantics or meanings themselves. No behaviors are specified for any token value.

No.	Name	Description	Value Space	Default Value
1	Resource ID	The identifier of the auxiliary resource.	Unique Identifier1	None Value is Required
2	Purpose	Indicates the purpose of the auxiliary resource.	Open Vocabulary	None Value is Required

1 This identifier should be globally unique, or at least unique in any scope in which sequenced activities might be used. The IMS Persistent, Location-Independent Resource Identifier Handbook [4] describes the recommended way to construct such an identifier.

SM.5   Rollup Rule Description

Rollup rule description (the set of attributes shown below) specifies the details of individual rule-based rollup behaviors for an activity. Rollup rules describe how values of the child activities influence the Objective Progress Information (TM.1.1) and Activity/Attempt Progress Progress Information (TM.1.2) for an activity. Rollup rule description information for an activity includes the associated data listed below.

Simple Sequencing processes may reference the rollup rules for any activity in the activity tree. Rollup rules are optional. Rollup rules are defined only where needed. Default data is used if the data is not instantiated for a given rule, if needed.

The data attributes describe one rule. Each activity may have an unlimited number of unordered rollup rules.

The general format of a rule can be expressed informally as: If child-activity set, condition set Then action.

• There is one child activity set that determines the child activities that are required for the condition to be true.
• Multiple conditions are permitted.
• The conditions may be combined with a single and combination (all conditions must be True) or a single or combination (only one condition must be True).
• Individual condition values may be negated before being combined in the rule evaluation.
• No other operators on the conditions are defined.
• Each condition references an item in the tracking model for the activity; conditions that reference objectives refer to the objective that has the attribute value Objective Contributes to Rollup value of True.
• There is one action that may result if the rollup conditions evaluate to True.
• Actions may result in setting of the Attempt Completion Status (TM.1.2.2) or Objective Satisfied Status (TM.1.1) (for the objective that has the attribute value Objective Contributes to Rollup (SM.6) value of True) for the activity.

The Rollup Child Activity Set, Rollup Conditions, Condition Combination, and Rollup Actions are tokens in a vocabulary. The tokens have no semantics or meanings themselves. The description of the condition or action is the complete definition of the required behavior.

No.	Name	Description	Value Space	Default Value
1	Rollup Child Activity Set	The set of children of the activity whose data values are used to evaluate the rollup condition. All - The rollup rule evaluates to True if and only if all of the children have a rollup condition (the result of the Condition Combination) value of True. Any - The rollup rule condition evaluates to True if any of the children have a rollup condition (the result of the Condition Combination) value of True. None - The rollup rule condition evaluates to True if none of the children have a rollup condition (the result of the Condition Combination) value of True. At Least Count - The rollup rule condition evaluates to True if at least the number of children specified by the Rollup Minimum Count attribute have a rollup condition (the result of the Condition Combination) value of True. At Least Percent - The rollup rule condition evaluates to True if at least the percentage of children specified in the Rollup Minimum Percent attribute have a rollup condition (the result of the Condition Combination) value of True.	Vocabulary	All
1.1	Rollup Minimum Count	The number of children activities associated with a Rollup Child Activity Set attribute value of At Least Count. This value is meaningless if the Rollup Child Activity Set value is not At Least Count.	Non Negative Integer	0
1.2	Rollup Minimum Percent	The percentage of children activities associated with a Rollup Child Activity Set attribute value of At Least Percent. This value is meaningless if the Rollup Child Activity Set value is not At Least Percent.	Real1 [0..1] Precision of at least 4 digits	0.0
2	Condition Combination	How rollup conditions are combined in evaluating the rule. All - The rule condition evaluates to True if and only if all of the individual rollup conditions evaluate to True (logical and). Any - The rule condition evaluations to True if any of the individual rollup conditions evaluates to True (logical or).	Vocabulary	Any
3	Rollup Conditions	An unordered collection of conditions for a rollup rule. A rollup rule may include multiple conditions.	Collection 0:N
3.1	Rollup Condition	A condition element for the rule. Satisfied - evaluates to True if the Objective Progress Status (TM.1.1) for the rolled up objective associated with the child activity is True and Objective Satisfied Status (TM.1.1) for the rolled up objective associated with the child activity is True. Objective Status Known - evaluates to True if Objective Progress Status (TM.1.1) for the rolled up objective associated with the child activity is True. Objective Measure Known - evaluates to True if the Objective Measure Status (TM.1.1) for the rolled up objective associated with the child activity is True. Completed - evaluates to True if the Attempt Progress Status (TM.1.2.2) for the child activity is True and the Attempt Completion Status (TM.1.2.2) for the child activity is True. Activity Progress Known - evaluates to True if the Activity Progress Status (TM.1.2.1) for the child activity is True and the Attempt Progress Status (TM.1.2.2) for the child activity is True. Attempted - evaluates to True if the Activity Progress Status (TM.1.2.1) for the child activity is True and the Activity Attempt Count (TM.1.2.1) for the child activity is positive (i.e., the child activity has been attempted). Attempt Limit Exceeded - evaluates to True if the Activity Progress Status (TM.1.2.1) for the child activity is True and the Limit Condition Attempt Limit Control (SM.3) for the child activity is True and the Activity Attempt Count (TM.1.2.1) for the child activity is equal to or greater than the Limit Condition Attempt Limit (SM.3) for the child activity. Time Limit Exceeded - evaluates to True if the Activity Progress Status (TM.1.2.1) for the child activity is True and any of the tracked durations for the child activity (Activity Absolute Duration, Activity Experienced Duration, Attempt Absolute Duration, Attempt Experienced Duration) exceed the corresponding duration Limit Condition values for the child activity (SM.3 - Limit Condition Activity Absolute Duration, Limit Condition Activity Experienced Duration, Limit Condition Attempt Absolute Duration, Limit Condition Attempt Experienced Duration) and the associated Limit Condition control value (SM.3 - Limit Condition Activity Absolute Duration Control, Limit Condition Activity Experienced Duration Control, Limit Condition Attempt Absolute Duration Control, Limit Condition Attempt Experienced Duration Control) for the child activity is True. Outside Available Time Range - evaluates to True if the current time is before or after the corresponding time Limit Condition values for the child activity (SM.3 - Limit Condition Begin Time, Limit ConditionEnd Time) and the associated Limit Condition control value (SM.3 - Limit Condition Begin Time Control, Limit Condition End Time Control) for the child activity is True. Never - always evaluates to False.	Vocabulary	Never
3.2	Rollup Condition Operator	The unary logical operator to be applied to the condition. Not - The corresponding condition is negated in rule evaluation. NO-OP - The corresponding condition is used as is in rule evaluation.	Vocabulary	NO-OP
4	Rollup Action	The desired rollup behavior if the rule evaluates to True. Satisfied - The Objective Progress Status (TM.1.1) for the rolled up objective associated with the activity is set to True. The Objective Satisfied Status(TM.1.1) for the rolled up objective associated with the activity is set to True. Not Satisfied - The Objective Progress Status (TM.1.1) for the rolled up objective associated with the activity is set to True. The Objective Satisfied Status (TM.1.1) for the rolled up objective associated with the activity is set to False. Completed - The Attempt Progress Status (TM.1.2.2) for the activity is set to True. The Attempt Completion Status (TM.1.2.2) for the activity is set to True. Incomplete - The Attempt Progress Status (TM.1.2.2) for the activity is set to True. The Attempt Completion Status (TM.1.2.2) for the activity is set to False.	Vocabulary	Satisfied

1 The value is normalized between 0 and 1.

SM.6   Objective Description

The objective description (the set of attributes shown below) defines the learning objective(s) associated with an activity.

Each activity may have an unlimited number of learning objectives. The tracking model (see Tracking Model TM) defines a set of data that records the satisfaction status (e.g., passed/failed) and measure (e.g., score) for each objective, for each attempt on the activity. The meaning of a learning objective is not defined in this model; it is defined only in terms of its ID and its association with an activity.

Simple Sequencing processes may reference the local objective information for any activity. The use of Objective Maps (described in SM.7) allows Simple Sequencing processes to also reference objective information for globally shared objectives. An activity will have local objective information for each objective associated with the activity. An activity must have at least one objective; if one is not defined in the sequencing description associated with the activity, one will be instantiated for the purposes of sequencing. Each activity must have one and only one objective that contributes to rollup; if one is not defined in the sequencing description associated with the activity, one will be instantiated for the purposes of sequencing.

The Objective ID is required if the activity has more than one objective or if the objective information for the activity is to be shared with another activity.

No.	Name	Description	Value Space	Default Value
1	Objective ID	The identifier of an objective associated with the activity. The ID is a link to the corresponding objective information.	Unique Identifier1	NoneRequired Value
2	Objective Satisfied by Measure	Indicates that the Objective Minimum Satisfied Normalized Measure is to be used (True or False) in place of any other method to determine if the objective associated with the activity has been satisfied.	Boolean	False
3	Objective Minimum Satisfied Normalized Measure	The minimum satisfaction measure for the objective, normalized between -1..1 (inclusive). If the Objective Measure Status (TM.1.1) for the objective is True and the Objective Normalized Measure (TM.1.1) for the objective exceeds this value, the Objective Progress Status (TM.1.1) is set to True and the Objective Satisfied Status (TM.1.1) is set to True. If the Objective Measure Status (TM.1.1) for the objective is True and the Objective Normalized Measure (TM.1.1) for the objective is less than this value, the Objective Progress Status (TM.1.1) is set to True and the Objective Satisfied Status (TM.1.1) is set to False. The value is unreliable unless Objective Satisfied by Measure is True.	Real [-1..1] Precision of at least 4 significant decimal digits	1.0
4	Objective Contributes to Rollup	Indicates that the Objective Satisfied Status (TM.1.1) and Objective Normalized Measure (TM.1.1) for the objective are used (True or False) during rollup.	Boolean	False

1 This identifier should be globally unique, or at least unique in any scope in which sequenced activities might be used. The IMS Persistent, Location-Independent Resource Identifier Handbook [4] describes the recommended way to construct such an identifier.

SM.7   Objective Map

The objective map description (the set of attributes shown below) defines a mapping of an activity's local objective information to and from a shared global objective.

Each activity may have an unlimited number of objective maps.

By default, no objective information is shared between activities. If objective mapping is desired, each activity must define a set of Objective Maps to describe how local objective information is mapped to shared global objectives. The Objective Map data is evaluated whenever local objective information is processed, as described in the tracking model (see Tracking Model TM) behaviors. For any given local objective, a 'read' map with at most one global objective may be defined. Also, for any global objective, for any activity, a 'write' map with at most one local objective can be defined.

Simple Sequencing processes may reference the objective map data for any activity. Objective mapping does not occur if objective map data is not defined. Default data is used if the data is not instantiated for the activity, if needed.

No.	Name	Description	Value Space	Default Value
1	Activity Objective ID	The identifier of the local objective associated with the activity.	Unique Identifier1	None Value is Required
2	Target Objective ID	The identifier of global shared objective targeted for the mapping.	Unique Identifier2	None Value is Required
3	Read Objective Satisfied Status	Indicates that the Objective Satisfied Status (TM.1.1) for the identified local objective (Activity Objective ID), should be retrieved (True or False) from the identified shared global objective (Target Objective ID), when the progress for the local objective is undefined - Objective Progress Status (TM.1.1) for the identified local objective (Activity Objective ID) is False. This operation does not change the Objective Information associated with the local objective.	Boolean	True
4	Write Objective Satisfied Status	Indicates that the Objective Progress Status (TM.1.1) and Objective Satisfied Status (TM.1.1) values, for the identified local objective (Activity Objective ID), should be transferred (True or False) to the identified global shared objective (Target Objective ID), upon termination of an attempt on the activity.	Boolean	False
5	Read Objective Normalized Measure	Indicates that the Objective Normalized Measure (TM.1.1) for the identified local objective (Activity Objective ID), should be retrieved (True or False) from the identified shared global objective (Target Objective ID), when the measure for the local objective is undefined - Objective Measure Status (TM.1.1) for the identified local objective (Activity Objective ID) is False. This operation does not change the Objective Information associated with the local objective.	Boolean	True
6	Write Objective Normalized Measure	Indicates that the Objective Measure Status (TM.1.1) and Objective Normalized Measure (TM.1.1) values, for the identified local objective (Activity Objective ID), should be transferred (True or False) to the identified global shared objective (Target Objective ID), upon termination of an attempt on the activity.	Boolean	False

1 This identifier should be globally unique, or at least unique in any scope in which sequenced activities might be used. The IMS Persistent, Location-Independent Resource Identifier Handbook [4] describes the recommended way to construct such an identifier. 2 This identifier should be globally unique, or at least unique in any scope in which sequenced activities might be used. The IMS Persistent, Location-Independent Resource Identifier Handbook [4] describes the recommended way to construct such an identifier.

SM.8   Rollup Controls

Rollup controls (the set of attributes shown below) include descriptions of the types of rollup behaviors specified for an activity. Rollup controls for an activity include the associated data listed below.

Simple Sequencing processes may reference the rollup control data for any activity in the activity tree. Rollup control data need not be defined for each activity in the activity tree. Default data is used if the data is not instantiated for the activity, if needed.

No.	Name	Description	Value Space	Default Value
1	Rollup Objective Satisfied	Indicates that Objective Satisfied Status (TM.1.1) for the objective (which has Objective Contributes to Rollup (SM.6) equal to True) associated with the activity is included (True or False) in the rollup for its parent activity.	Boolean	True
2	Rollup Objective Measure Weight	A weighting factor applied to the Objective Normalized Measure (TM.1.1) for the objective (which has Objective Contributes to Rollup (SM.6) equal to True) associated with the activity used during rollup for its parent activity.	Real [0..1] Precision of at least 4 significant decimal digits	1.0
3	Rollup Progress Completion	Indicates that the Attempt Completion Status (TM.1.2.2) value for the activity is included (True or False) in the rollup for its parent activity.	Boolean	True

SM.9   Selection Controls

Selection controls (the set of attributes shown below) include descriptions of how the children of an activity should be selected during the sequencing process. Selection controls for an activity include the associated data listed below.

Simple Sequencing processes may reference the selection control data for any activity in the activity tree. Selection control data is optional. Selection control data need not be defined for each activity in the activity tree. Default data is used if the data is not instantiated for the activity, if needed.

No.	Name	Description	Value Space	Default Value
1	Selection Timing	Indicates when selection should occur. Never - Selection is never applied; all of the children of the activity are selected by default. Once - Selection is applied before the first attempt on an activity. On Each New Attempt - Selection is applied before each new attempt on an activity. The On Each New Attempt option and its associated behavior is not specified in this version of the Simple Sequencing Specification1.	Vocabulary	Never
2	Selection Count Status	Indicates the selection count data is (True or False) meaningful for the activity.	Boolean	False
3	Selection Count	Indicates the number of child activities that must be selected from the set of child activities associated with the activity. If Selection Count is larger than the number of child activities, all child activities are selected. This value is unreliable unless Selection Count Status is True. If Selection Count Status is False all child activities are selected.	Non Negative Integer	0

1 Although the selection of child activities 'on each new attempt' is a desired feature, when to perform the operation is not well defined.

SM.10   Randomization Controls

Randomization controls (the set of attributes shown below) include descriptions of how the children of an activity should be ordered during the sequencing process. Randomization controls for an activity include the associated data listed below.

Simple Sequencing processes may reference the randomization control data for any activity in the activity tree. Randomization control data is optional. Randomization control data need not be instantiated for each activity in the activity tree. Default data is used if the data is not instantiated for the activity.

No.	Name	Description	Value Space	Default Value
1	Randomization Timing	Indicates when the ordering of the children of the activity should occur. Never - Randomization is never applied. Once - Randomization is applied before the first attempt on the activity. On Each New Attempt - Randomization is applied before each new attempt on the activity.	Vocabulary	Never
2	Randomize Children	Indicates that the order of the child activities is randomized (True or False).	Boolean	False

SM.11   Delivery Controls

Delivery controls (the set of attributes shown below) describe actions and controls used when an activity is delivered, i.e., Objective, Activity, and Attempt Progress Data are recorded when the activity is delivered. Delivery controls for an activity include the associated data listed below.

Simple Sequencing processes may reference the delivery control data for any activity in the activity tree. Delivery controls are optional. Delivery data need not be defined for each activity in the activity tree. Default data is used if the data is not instantiated for the activity, if needed.

No.	Name	Description	Value Space	Default Value
1	Tracked	Indicates that Objective Progress Information and Activity/Attempt Progress Information (TM) for the attempt should be recorded (True or False) and the data will contribute to the rollup for its parent activity. How the data is tracked and recorded is not specified.	Boolean	True
2	Completion Set by Content	Indicates that the Attempt Completion Status (TM.1.2.2) for the activity will be set by the content object (True or False). A False value indicates that default rules will be used to set progress data. For a True value, how, if or when the completion data is set is not specified.	Boolean	False
3	Objective Set by Content	Indicates that the Objective Satisfied Status (TM.1.1) for the activity's associated objective that has the Objective Contributes to Rollup (SM.6) value of True will be set by the content object (True or False). A False value indicates that default rules will be used to set objective information. For a True value, how, if or when the objective information is set is not specified.	Boolean	False

SM.12   Sequencing Description

The complete set of sequencing information (all of the items described above) is associated with each activity in the activity tree. The table lists all of the elements in the overall sequencing description and their multiplicities.

The sequencing description model describes the data that specifies the intended sequencing behavior. This data is used by a system that delivers sequenced activities. How this information is encoded, stored, represented, or bound is outside the scope of this specification. The overall sequencing definition model only describes a set of related data items and internal constraints on the values of those items.

There is no requirement that the value for any specific sequencing definition model data item exist. There is a defined default or initial value for most attributes. When a data item does not exist and its attributes are required for some process, the default value is supplied upon reference if the data value does not exist.

The mechanisms used to create or maintain the sequencing definition model data are not specified as part of the information model.

An implementation must be capable of representing the range of values described. There are no additional requirements on implementing the sequencing definition model.

The sequencing behavior model, navigation behavior model, termination behavior model, rollup behavior model, selection and randomization behavior model and delivery behavior model (see Sequencing Behavior Model SB, Navigation Behavior Model NB, Termination Behavior Model TB, Rollup Behavior Model RB, Selection and Randomization Behavior Model SR, Delivery Behavior Model DB) describe how a sequencing system uses a sequencing definition instance for an activity tree to control the sequencing and delivery of activities.

No.	Name	Description	Value Space	Default Value
1	Sequencing Control Modes	Describes the types of sequencing behaviors specified for an activity.	Sequencing Control Mode	0..1
2	Sequencing Rules	Describes the details of individual rule-based sequencing behaviors for an activity.	Ordered set of Sequencing Rule Description	0..N
3	Limit Conditions	Describes the constraints on the access to an activity based on time of day, time spent on the activity and number of attempts.	Limit Conditions Description	0..1
4	Auxiliary Resources	Describes the auxiliary resources available while the activity is active.	Auxiliary Resource Description	0..N
5	Rollup Rules	Describes the details of individual rule-based rollup behaviors for an activity.	Rollup Rule Description	0..N
6	Objectives	Describes an unordered collection of objectives associated with an activity.	Objective Description	0..N
7	Objective Maps	Describes mappings of local objective information for an activity to a global shared objective.	Objective Map	0..N
8	Rollup Controls	Describes the types of rollup behaviors specified for an activity.	Rollup Controls	0..1
9	Selection Controls	Describes how the children of an activity should be selected during the sequencing process.	Selection Controls	0..1
10	Randomization Controls	Describes how the children of an activity should be ordered during the sequencing process.	Randomization Controls	0..1
11	Delivery Controls	Describes actions and controls used when an activity is delivered.	Delivery Controls	0..1

TM.   Tracking Model

Simple Sequencing processes uses information about the results of a learner's interactions with activities, and the learner's record for objectives (e.g., completion, measure) to control the selection and sequencing of other activities. The sequencing behaviors are defined in terms of a limited set of specific data attributes that describe the results of the learner's interactions. The defined set of attributes used by Simple Sequencing is called the "tracking model".

The tracking model consists of:

• An information model, defined in two parts:
  • Objective Progress Information - information about the results of the learner's interactions related to an objective.
  • Activity / Attempt Progress Information - information about a learner's attempts at an activity.
• Behaviors - requirements on instantiation and use of the tracking information model.

TM.1   Tracking Information Model

The tracking information model describes the data used by a system that delivers sequenced activities. How this information is encoded, stored, represented, or bound is outside the scope of this specification. The tracking information model only describes a set of related data items and internal constraints on the values of those items.

An implementation must be capable of representing the range of values described. There are no additional requirements on implementing the information model.

The tracking model behaviors description states requirements for the instantiation and use of the information model.

TM.1.1   Objective Progress Information

Objective progress information includes results of the learner's interactions related to an objective. Tracking information for an objective includes the associated data (i.e., the objective information) listed below. How the tracking information is associated with an objective is not specified.

Simple Sequencing descriptions may reference objective information for any local objective associated with any activity in the activity tree, or any shared global objective. Objective progress information should be instantiated for objectives referenced in the activity tree for each learner as appropriate.

No.	Name	Description	Value Space	Default Value
1	Objective Progress Status	Indicates the objective has a satisfaction value (True or False).	Boolean	False
2	Objective Satisfied Status	Indicates the objective is satisfied (True or False). The determination or meaning of satisfied or not satisfied is not defined in this model. The value is unreliable unless Objective Progress Status is True.	Boolean	False
3	Objective Measure Status	Indicates the objective has a measure value (True or False).	Boolean	False
4	Objective Normalized Measure	The measure (e.g., score) for the objective, normalized between -1..1 (inclusive). The mechanism to normalize a measure is not defined in this model. The value is unreliable unless Objective Measure Status is True.	Real [-1..1] Precision of at least 4 significant decimal digits	0.0

TM.1.2   Activity/Attempt Progress Information

TM. 1.2.1   Activity Progress Information

Activity progress information (the set of attributes shown below) describes a learner's progress on an activity. This information describes the cumulative progress information for an individual activity. Tracking information for an activity includes the data listed below.

Simple Sequencing descriptions may reference activity progress information for any activity in the activity tree. Activity progress information should be instantiated for each activity in the activity tree for each learner. The mechanism for determining an activity's duration is not defined in this model. How the activity progress information is associated with an activity is not specified.

No.	Name	Description	Value Space	Default Value
1	Activity Progress Status	Indicates the activity progress information is (True or False) meaningful for the activity.	Boolean	False
2	Activity Absolute Duration	The cumulative duration of all attempts on the activity, i.e., the time from the initial start of the activity to the end of the activity. The mechanism for determining the duration is not defined in this model. The value is unreliable unless Activity Progress Status is True.	Duration Accuracy 0.1 second	0.0
3	Activity Experienced Duration	The cumulative experienced duration of all attempts on the activity, i.e., the time from the initial start of the activity to the end of the activity, not including any time elapsed while the activity is suspended (i.e., when the activity is not being experienced or is inactive). The mechanism for determining the duration of the suspend time is not defined in this model. The value is unreliable unless Activity Progress Status is True and the activity is a leaf.	Duration Accuracy 0.1 second	0.0
4	Activity Attempt Count	The number of attempts on the activity. The count includes the current attempt, i.e., 0 means the activity was not attempted and 1 or greater means it either is in progress or completed. The value is unreliable unless Activity Progress Status is True.	Non Negative Integer	0

TM. 1.2.2   Attempt Progress Information

Attempt progress information (the set of attributes shown below) describes a learner's progress for a unique attempt on an activity. This information describes the progress information for one attempt on an individual activity. Tracking information for an attempt on an activity includes the data listed below.

Simple Sequencing descriptions may reference attempt progress for any activity in the activity tree. Attempt progress information should be instantiated for each new attempt for each activity in the activity tree for each learner. The mechanism for determining an activity's duration is not defined in this model. How the attempt progress information is associated with an activity is not specified.

No.	Name	Description	Value Space	Default Value
1	Attempt Progress Status	Indicates the attempt progress information (True or False) is meaningful for the activity attempt. The value is unreliable unless Activity Attempt Count (TM.1.2.1) is greater than (>) 0.	Boolean	False
2	Attempt Completion Amount1	The measure of the completion of the attempt on the activity, normalized between 0..1 (inclusive) where 1 means the activity attempt is complete and any lesser value means the activity attempt is not complete. The mechanism to define the completion amount is not defined in this model. The value is unreliable unless Attempt Progress Status is True.	Real [0..1] Precision of at least 4 significant decimal digits	0.0
3	Attempt Completion Status	Indicates the activity attempt is completed (True or False). The determination or meaning of completed or incomplete is not defined in this model. The value is unreliable unless Attempt Progress Status is True.	Boolean	False
4	Attempt Absolute Duration	The duration of the attempt on the activity, i.e., time from the start of the attempt to the end of the attempt. The mechanism for determining the duration is not defined in this model. The value is unreliable unless Attempt Progress Status is True.	Duration Accuracy 0.1 second	0.0
5	Attempt Experienced Duration	The experienced duration of the attempt on the activity, i.e., the time from the start of the attempt to the end of the attempt, not including elapsed time while the activity attempt is suspended (i.e., when the activity attempt is not being experienced or is inactive). The mechanism for determining the duration or the suspend time is not defined in this model. The value is unreliable unless Attempt Progress Status is True.	Duration Accuracy 0.1 second	0.0

1 In SS v1.0, Attempt Completion Amount cannot be evaluated as a rule condition and is not managed by the sequencing engine.

TM.2   Tracking Model Behaviors

The objective progress information applies to an objective. It should be instantiated for each local objective for each learner, and should be initialized for each new attempt on each activity. It should be instantiated once for each shared global objective for each learner.

The activity progress information is for an activity. It should be instantiated for each activity for each learner.

The attempt progress information is for an attempt. It should be instantiated for each learner, and should be initialized for each new attempt on each activity

There is no requirement that the value for any specific tracking data item exist. There is a defined default or initial value for each data item. The default value shall be supplied upon reference if the data item does not exist.

Activity and Attempt durations (absolute and experienced) should be maintained by the LTS. The mechanisms or processes for managing durations is not defined in this document. The only requirements for duration values are:

• The Activity Absolute Duration (TM.1.2.1) shall equal the sum of all of the activity's Attempt Absolute Durations - any absolute duration will occur during some attempt.
• The Activity Absolute Duration (TM.1.2.1) of a parent activity shall equal the sum of all of its children's Activity Absolute Durations. See Figure TM.1.

Figure TM.1 illustrates how Activity Experienced Duration and Activity Absolute Duration are tracked. It shows the tracking of one attempt on one activity. An attempt on an activity begins; is suspended; and is resumed twice, finally terminating without a suspend. Absolute duration is accumulated from the time the activity begins until it exits. Experienced duration is accumulated from when each attempt on the activity begins until when it is suspended. Accumulation resumes when the attempt is resumed, and continues until it is suspended. Accumulation again resumes when the attempt is again resumed, and continues until the activity terminates.

As only one attempt on the activity is shown, the attempt durations (experienced and absolute) are the same as the activity durations (experienced and absolute).

The timeline is independent of the state of the sequencing session. The attempts may occur across multiple sequencing sessions.

The objective ID and an associated activity identifier are required to reference a specific objective. If an activity only has one local objective and that objective is not shared with any other activity, only the activity identifier is required.

When a local objective's data is undefined (either Objective Progress Status (TM.1.1) or Objective Measure Status (TM.1.1) are False) and a 'read' Objective Map (SM.7) is associated with the objective, the corresponding shared global objective information is used. This is an access-only operation and does not affect the local objective information for the activity. The reference to a global objective only uses the objective ID to locate the actual objective information.

Simple Sequencing processes access local objective information and the attempt progress information only for the most recent attempt at an activity by a learner. If the learner is interacting with the activity, for the purposes of the tracking model, the most recent attempt is the current interaction or current attempt. Otherwise, the most recent attempt is the last fully completed interaction with the activity (if there was one), i.e., the last completed attempt.

Accessing tracking information for the most recent attempt at an activity is controlled by the Use Current Attempt Objective Information (SM.1) and Use Current Attempt Progress Information (SM.1) elements. If either of these elements for an activity is True, the tracking model will not maintain the most recent attempt tracking data (although an implementation is free to retain the historical tracking information) for any of the activity's children, unless those attempts occurred while the current active attempt on the activity is in progress, i.e., the attempt on the child activity occurred while the current attempt on its parent activity was active.

There is no requirement that the attempt progress information be maintained for any attempt other than the most recent attempt. Simple Sequencing makes no requirement to maintain prior history for objective information or overall activity information.

There are no requirements on how or when the values of the tracking data are set and updated for the learner. Simple Sequencing relies only on the "current" values in the information model. Generally, learner interactions with an activity will result in appropriate changes to the tracking data, but these mechanics are not specified.

The overall rollup process (see Rollup Behavior RB) defines how tracking data for one activity contributes to the tracking data for ancestors of that activity. How the rollup process uses the tracking data is not specified here but is detailed in the description of the behavior of the rollup process.

The termination, sequencing, and delivery processes (see TB, Sequencing Behavior SB, and Delivery Behavior DB) use the tracking data for elements of the activity tree to determine what happens when an attempt on an activity ends and how subsequent activities are sequenced and delivered to the learner. How the processes use the tracking data are not specified here but are detailed in the descriptions of the behavior of these processes.

The mechanisms used to record and set the tracking data are not specified as part of the information model.

AM.   Activity State Model

Simple Sequencing processes uses information about the state or status of the learner's interactions with activities. These attributes are used to control the overall sequencing process, but are not referenced in any specific sequencing definition or sequencing rule. The defined set of state attributes used by Simple Sequencing is called the "activity state model".

The activity state model consists of:

• An information model, defined in two parts:
  • Activity State Information - information that describes the state of the most recent attempt at an activity.
  • Global State Information - information that describes the overall state of sequencing.
• Behaviors - requirements on instantiation and use of the activity state model.

AM.1   Activity State Information Model

The activity state information model describes the data used by a system that delivers sequenced activities. How this information is encoded, stored, represented, or bound is outside the scope of this specification. The state information model only describes a set of related data items and internal constraints on the values of those items.

An implementation must be capable of representing the range of values described. There are no additional requirements on implementing the activity state information model.

The activity state model behaviors description gives requirements for the instantiation and use of the activity state information model.

AM.1.1   Activity State Information

Activity state information (the set of attributes shown below) describes a learner's state or status for an activity.

Simple Sequencing descriptions and behaviors may reference activity state data for any activity in the activity tree. Activity state data should be instantiated for each activity in the activity tree for each learner. How the activity state information is associated with an activity is not specified.

The activity state values of Activity is Active and Activity is Suspended cannot both be True at the same time.

No.	Name	Description	Value Space	Default Value
1	Activity is Active	Indicates that an attempt is currently in progress for the activity, i.e. the activity has been delivered to the learner and has not been terminated, or the activity is an ancestor of the Current Activity (AM.1.2) (True or False).	Boolean	False
2	Activity is Suspended	Indicates the activity is currently suspended (True or False).	Boolean	False
3	Available Children	A list indicating the ordering of the available child activities for the activity.	Ordered List of Activities	All children

AM.1.2   Global State Information

Global state information (the set of attributes shown below) describes a learner's state or status within the overall sequenced learning experience.

Global state information should be instantiated once for an activity tree for each learner. How the global state information is associated with an activity tree is not specified.

No.	Name	Description	Value Space	Default Value
1	Current Activity	Indicates the current activity. If an activity is being experienced by the learner, the current activity is the activity delivered by the most recently completed Content Delivery Environment Process (see Delivery Behavior DB). If an activity is not being experienced by the learner, the current activity is the last activity identified to terminate by the most recently completed Termination Request Process (see Termination Behavior TB), or the undeliverable target activity of the last successful Choice Sequencing Request Process (see Sequencing Behavior SB)	Activity	None
2	Suspended Activity	Indicates the activity from which a Suspend All navigation request was triggered.	Activity	None

AM.2   Activity State Model Behaviors

The activity state data is for an activity. It should be instantiated for each activity for each learner.

The global state data is for the overall sequencing process. It should be instantiated for the entire sequencing process for each learner.

There is no requirement that the value for any activity state or global state data item exist. There is a defined default or initial value for each data item. The default value shall be supplied upon reference if the data item does not exist.

The mechanisms used to record and set the activity state data are not specified as part of the information model.

The navigation, termination, rollup, selection and randomization, sequencing, and delivery processes (see Navigation Behavior NB, Termination Behavior TB, Selection and Randomization Behavior SR, Sequencing Behavior SB, Rollup Behavior RB, Delivery Behavior DB) use the activity data for elements of the activity tree and the global state data to determine the activities that are sequenced and delivered to the learner. How these processes use the activity and global state data are not specified here but are detailed in the descriptions of the behavior of these processes.

Although the detailed behavior for changing the Current Activity is described in the termination, sequencing, and delivery processes (see Termination Behavior TB, Sequencing Behavior SB, and Delivery Behavior DB) that follow, the state transition diagram in Figure AM.1 for the Current Activity is intended to provide a summary of the behaviors.

Figure AM.1 depicts the state transitions of the Current Activity; it summarizes the effects of the various sequencing processes on the Current Activity and the activity's state.

Begin Loop:

Starting at the star, the sequencer assumes that a content resource has been delivered to the learner; the resource's associated activity is the Current Activity (AM.1.2) - it must be leaf of the activity tree and it is currently active. All ancestors (along the 'active path') of the Current Activity are also active, because attempts on an activity only occur within the context of attempts on the activity's ancestors.

The state of the activity tree remains like this until some navigation request triggers the Overall Sequencing Process (see Overall Sequencing Process OP). If the navigation request is valid, it will result in a termination request to end the attempt on the Current Activity - its Activity State attribute of Activity is Active becomes false. The Current Activity remains the leaf activity.

When an attempt on a leaf activity ends, the system may indicate the state of the termination was to suspend the activity - this is done in the End Attempt Process (UP.4). If the system indicates this, the Activity is Suspended (AM.1.1) for the leaf activity (still the Current Activity) becomes true.

During Termination Behavior, Exit Action Rules (see Sequencing Exit Action Rules Subprocess TB.2.1) are evaluated on all of the ancestors of the Current Activity. The result of this subprocess will be that either the leaf activity remains the Current Activity, or an ancestor of the leaf activity becomes the Current Activity.

During the Termination Behavior, post condition rules are evaluated (see Sequencing Post Condition Rules Subprocess TB.2.2) only on the Current Activity, which is either the leaf activity or the activity identified during the Sequencing Exit Action Rule Subprocess, if that Current Activity is not suspended.

The Sequencing Behavior processes any pending sequencing request, which may result in a delivery request. It is possible, during the evaluation of a Choice sequencing request (see Choice Sequencing Request Process SB.2.9), the the process succeeds in reaching the target activity, but the activity is not deliverable, e.g., the activity is not a leaf. If this happens, the Current Activity is moved to the target of the successful Choice sequencing request and any intermediate activities are terminated.

The Delivery Behavior validates any pending delivery request. If the delivery request is validated, the Content Delivery Environment Process (DB.2) is invoked. During this process, the activity identified by the delivery request becomes the Current Activity and an attempt is started (or resumed) on it - the Current Activity has Activity is Active equal to true and Activity is Suspended equal to false.

Repeat Loop

OP.  Overall Sequencing Process

The overall sequencing process combines all of the other elements of Simple Sequencing to produce the complete sequencing, delivery and control of learning experience and relates all of the other Simple Sequencing processes and behaviors.

• Navigation Behavior Model - The Simple Sequencing process that evaluates a navigation request and determines the exit and sequencing requests that should be processed to identify and deliver content to the learner (see Navigation Behavior NB).
• Termination Behavior Model - The Simple Sequencing process that processes a termination request to terminate or suspend an activity or set of activities (see Termination Behavior TB).
• Selection and Randomization Behavior Model - The Simple Sequencing process that selects and reorders activities before being used in sequencing (see Selection and Randomization SR).
• Sequencing Behavior Model - The Simple Sequencing process that evaluates a sequencing request in terms of the content model described by the activity tree and determines the actual content object that should be delivered to the learner (see Sequencing Behavior SB).
• Delivery Behavior Model - The Simple Sequencing process that validates that the content resources for the identified activity may be delivered, i.e., all of the conditions that apply to the delivery of the content for the activity and attempt still hold (see Delivery Behavior DB).

The overall sequencing process describes only a logical workflow. It makes no assumption on how or when the various steps of the process are invoked, or in what order they are processed.

The behavior of the sequencing process is defined in terms of different processes:

• Navigation Request Process - processes the navigation request to identify the corresponding sequencing and termination requests.
• Termination Request Process - processes the termination request, sets the corresponding activity state, evaluates exit and post condition rules, and may identify a sequencing request.
• Selection and Randomization Processes - select and order activities as defined prior to processing a sequencing request.
• Sequence Request Process - processes the sequencing request that controls all sequencing behavior, combining:
  • Start Sequencing Request Process - processes a Start sequencing request.
  • Resume All Sequencing Request Process - processes a Resume All sequencing request.
  • Continue Sequencing Request Process - processes a Continue sequencing request.
  • Previous Sequencing Request Process - processes a Previous sequencing request.
  • Choice Sequencing Request Process - processes a Choice sequencing request.
  • Retry Sequencing Request Process - processes a Retry sequencing request.
  • Exit Sequencing Request Process - processes an Exit sequencing request.
• Delivery Request Process - processes a delivery request.
• Content Delivery Environment Process - manages the actual delivery of content resources to the learner.

OP.1  Overall Behavior

The overall behavior functions within the scope of some Learning Technology System (LTS), e.g., an LMS, that has identified learners and internal representations of content activity trees, sequencing descriptions, content resources, and information models used to track the learner and record state. How these actual information models are implemented or initialized is not specified.

An implementation must be capable of representing the processes described and have the implemented processes exhibit the behavior described. There are no additional requirements on implementing the overall sequencing behavior.

When the learner initiates a learning experience, the LTS will generate either a Start or Resume All navigation request. Other interactions with the LTS will result in other navigation requests. How or when a navigation request is generated is not specified.

The sequencing system operates in a loop, awaiting external navigation requests, processing these, possibly delivering content, and then waiting for additional requests.

The sequencing system continues operations until terminated by the controlling LTS.

The navigation requests are translated by the navigation process into termination and sequencing requests. If the learner is experiencing an activity, the navigation request results in the current activity being terminated by the termination process when it processes the termination request - only one activity may be active. Sequencing rules in the termination process may override the sequencing request. The rollup process is performed to propagate results from an activity to its ancestor activities. The sequencing request is processed by the sequencing process to determine the next activity in the sequence, i.e., the next activity to present to the learner. If the sequencing process identifies an activity, the designated activity is passed to the delivery process. The delivery process will verify that the activity should be delivered, i.e., that the limit conditions and sequencing rules applied to the activity permit it to be delivered. If the delivery process identifies an activity for delivery, the auxiliary resource descriptions are provided to the LTS, content resources associated with the identified activity are presented to the learner, and the learner's interactions with the content may be tracked by the LTS (how this tracking is done is not specified in Simple Sequencing). Once the content has been delivered to the learner, the Overall Sequencing Process waits for the next navigation request.

Figure OP.1 depicts the process flow of the Overall Sequencing Process.

Figure OP.2 illustrates a portion of a sequencing session. A sequencing session may be triggered in one of three ways:

1. A Start sequencing request.
2. A Resume All sequencing request.
3. A Choice sequencing request prior to either a Start or Resume All sequencing request.

A sequencing session ends normally when an Exit sequencing request is processed from the root of the activity tree.

The overall behavior assumes one request is fully processed before another request is processed. There is no constraint on the timing of when requests are received. The description does not detail or otherwise make any assumptions as to how the requests are serialized or how any request may preempt or terminate any in-process request.

The Overall Sequencing Process is specified by the following pseudo code. The pseudo code describes only the processing. How this process is implemented or how information is encoded, stored, represented, or bound is outside the scope of this specification. The Overall Sequencing Process only describes the expected behavior that an implementation will exhibit. See Figure OP.2.

Overall Sequencing Process:
Reference: Section: Content Delivery Environment Process DB.2 Delivery Request Process DB.1.3 Navigation Request Process NB.2.1 Sequencing Request Process SB.2.12 Termination Request Process TB.2.3
1.	Loop - Wait for a navigation request
1.1.	Apply the Navigation Request Process to the navigation request
1.2.	If the Navigation Request Process returned navigation request Not Valid Then
1.2.1.	Handle the navigation request error	Behavior not specified
1.2.2.	Continue Loop - wait for the next navigation request
	End If
1.3.	If there is a termination request Then	If the current activity is active, end the attempt on the current activity.
1.3.1.	Apply the Termination Request Process to the termination request
1.3.2.	If the Termination Request Process returned termination request Not Valid Then
1.3.2.1.	Handle the termination request error	Behavior not specified
1.3.2.2.	Continue Loop - wait for the next navigation request
	End If
1.3.3.	If Termination Request Process returned a sequencing request Then
1.3.3.1.	Replace any pending sequencing request by the sequencing request returned by the Termination Request Process	There can only be one pending sequencing request. Use the one returned by the termination request process, if it exists.
	End If
	End If
1.4.	If there is a sequencing request Then
1.4.1.	Apply the Sequencing Request Process to the sequencing request
1.4.2.	If the Sequencing Request Process (SB.2.12) returned sequencing request Not Valid Then
1.4.2.1.	Handle the sequencing request error	Behavior not specified
1.4.2.2.	Continue Loop - wait for the next navigation request
	End If
1.4.3.	If the Sequencing Request Process returned a request to end the sequencing session Then
1.4.3.1.	Exit Overall Sequencing Process - the sequencing session has terminated; return control to LTS	Exiting from the root of the activity tree ends the sequencing session; return control to the LTS
	End If
1.4.4.	If the Sequencing Request Process did not identify an activity for delivery Then
1.4.4.1.	Continue Loop - wait for the next navigation request
	End If
1.4.5.	delivery request is for the activity identified by the Sequencing Request Process
	End If
1.5.	If there is a delivery request Then
1.5.1.	Apply the Delivery Request Process to the delivery request
1.5.2.	If the Delivery Request Process returned delivery request Not Valid Then
1.5.2.1.	Handle the delivery request error	Behavior not specified
1.5.2.2.	Continue Loop - wait for the next navigation request
	End If
1.5.3.	Apply the Content Delivery Environment Process to the delivery request
	End If
2.	End Loop - wait for the next navigation request

NB.   Navigation Behavior Model

When a learner is interacting with a learning experience through a user interface, each leaner request to move through the content or branch within the learning experience results in a "navigation event", e.g., a click to move to the next activity. These events map to a set of "navigation requests". In turn, each navigation request maps to an "termination request" and a "sequencing request" that will be used to both terminate the attempt on the current activity and determine the 'next' activity in the learning experience. There is a mapping or resolution process that converts a navigation request into the corresponding termination and sequencing requests. The process of evaluating the navigation request and identifying the appropriate termination and sequencing requests (or returning an error) is called the "navigation process".

The navigation process makes no assumptions as to how or when a navigation request is generated. The navigation process makes no assumptions about user interfaces and rendering of navigation structures and controls, either within content objects or external to content objects. Mapping of a user interaction to the generation of a navigation requests outside of the scope of this specification. The navigation behavior is defined only for the navigation request.

The navigation process only provides minimal insurance that navigation requests are valid. If the navigation process declares a navigation request valid, it does not guarantee that any ensuing sequencing request will result in identifying a 'next' activity. The navigation process makes no assumptions on how or when the identified termination and sequencing requests will be processed. In most cases, the termination and sequencing requests will be passed immediately, by the overall sequencing process (see Overall Sequencing Process OP), to the termination and sequencing processes.

The overall sequencing process relates the navigation process to the termination, rollup, selection and randomization, sequencing, and delivery processes.

The navigation process only uses Sequencing Control Mode data from the sequencing definition model.

The navigation process does not use data from the tracking model.

The navigation process uses data from the activity state model.

The behavior of the navigation process is defined in terms of a single process:

• Navigation Request Process - processes the navigation request to identify the corresponding sequencing and termination requests.

NB.1   Navigation Requests

The navigation process responds to one of a set of different navigation requests. A navigation request defines the actions to be performed when the request is processed. The request names are tokens in a vocabulary. The names have no semantics or meanings themselves. The definition of the action is the complete definition of the required behavior.

Navigation Request	Action
Start	If the Current Activity (AM.1.2) is undefined, Issue a Start sequencing request.
Resume All	If the Current Activity (AM.1.2) is undefined and the Suspended Activity (AM.1.2) is defined, Issue a Resume All sequencing request.
Continue	If Activity is Active (AM.1.1) for the Current Activity (AM.1.2) is True, Issue an Exit termination request. Issue a Continue sequencing request.
Previous	If Activity is Active (AM.1.1) for the Current Activity (AM.1.2) is True, Issue an Exit termination request. Issue a Previous sequencing request.
Forward	Issue a sequencing request to traverse the "history-based activity record" forward in time. The corresponding sequencing request and associated behavior is not specified in this version of the Simple Sequencing Specification.
Backward	Issue a sequencing request to traverse the "history-based activity record" backward in time. The corresponding sequencing request and associated behavior is not specified in this version of the Simple Sequencing Specification.
Choice	If Activity is Active (AM.1.1) for the Current Activity (AM.1.2) is True, Issue an Exit termination request. Issue a Choice sequencing request. The request is accompanied by the identification of the target activity.
Exit	Issue an Exit termination request. Issue an Exit sequencing request. The current attempt on the Current Activity (AM.1.2) is terminated normally; the attempt is over. The termination of the activity was not the result of any other external navigation event (e.g., Continue, Previous, Choice).
Exit All	Issue an Exit All termination request. Issue an Exit sequencing request.
Suspend All	Issue a Suspend All termination request. Issue an Exit sequencing request. The current attempt on the Current Activity (AM.1.2) and all of its ancestors are terminated normally; the attempts are not over and the activities are not complete. The activities may be resumed at some time in the future (resumption is not a new attempt). A Simple Sequencing processor must record sufficient state and tracking information so that the activities may be resumed in the future.
Abandon	Issue an Abandon termination request. Issue an Exit sequencing request. The current attempt on the Current Activity (AM.1.2) is terminated abnormally and the activity is not complete. The attempt may not be resumed. There is no rollback of any tracking data.
Abandon All	Issue an Abandon All termination request. Issue an Exit sequencing request. The current attempt on the Current Activity (AM.1.2) and all of its ancestors are terminated abnormally and the activities are not complete. The attempts may not be resumed. There is no rollback of any tracking data.

NB.2   Navigation Behavior

The navigation behavior describes how a navigation processor interprets a navigation request to validate the navigation request and to identify the corresponding termination and sequencing requests.

An implementation must be capable of representing the processes described and have the implemented process exhibit the behavior described. There are no additional requirements on implementing the navigation behavior model.

NB.2.1   Navigation Request Process

The Navigation Request Process examines the navigation request, validates it and determines the corresponding termination and sequencing requests. The process may return a sequencing request. The process may optionally return an termination request. If the process does not return an termination request, there is no termination request for further processing. The process implements the behaviors that describe the navigation requests.

The Navigation Request Process for a navigation request is specified by the following pseudo code. The pseudo code describes only the navigation request processing and conversion to termination and sequencing requests. How this process is implemented or how information is encoded, stored, represented, or bound is outside the scope of this specification. The Navigation Request Process only describes the expected behavior that an implementation will exhibit.

Navigation Request Process (for a navigation request and possibly a specified activity, returns the validity of the navigation request; may return a termination request, a sequencing request, and/or a target activity):
Reference: Section: Current Activity AM.1.2 Sequencing Control Choice SM.1 Sequencing Control Choice Exit SM.1 Sequencing Control Flow SM.1 Sequencing Control Forward Only SM.1 Suspended Activity AM.1.2
1.	Case: navigation request is Start
1.1.	If the Current Activity is Not Defined Then	Make sure the sequencing session has not already begun.
1.1.1.	Exit Navigation Request Process (Navigation Request: Valid; Sequencing Request: Start; Termination Request: n/a; Target Activity: n/a)
1.2.	Else
1.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End If
	End Case
2.	Case: navigation request is Resume All
2.1.	If the Current Activity is Not Defined Then	Make sure the sequencing session has not already begun.
2.1.1.	If the Suspended Activity is Defined Then	Make sure the previous sequencing session ended with a suspend all request.
2.1.1.1.	Exit Navigation Request Process (Navigation Request: Valid; Sequencing Request: Resume All; Termination Request: n/a; Target Activity: n/a)
2.1.2.	Else
2.1.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End If
2.2.	Else
2.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End If
	End Case
3.	Case: navigation request is Continue
3.1.	If the Current Activity is Not Defined Then	Make sure the sequencing session has already begun.
3.1.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End If
3.2.	If the Current Activity is not the root of the activity tree And the Sequencing Control Flow for the parent of the Current Activity is True Then	Validate that a 'flow' sequencing request can be processed from the current activity.
3.2.1.	If the Activity is Active for the Current Activity is True Then	If the current activity has not been terminated, terminate the current the activity.
3.2.1.1.	Exit Navigation Request Process (Navigation Request: Valid; Termination Request: Exit; Sequencing Request: Continue; Target Activity: n/a)
3.2.2.	Else
3.2.2.1.	Exit Navigation Request Process (Navigation Request: Valid; Sequencing Request: Continue; Termination Request: n/a; Target Activity: n/a)
	End If
3.3.	Else
3.3.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)	Flow is not enabled or the current activity is the root of the activity tree.
	End If
	End Case
4.	Case: navigation request is Previous
4.1.	If the Current Activity is Not Defined Then	Make sure the sequencing session has already begun.
4.1.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End If
4.2.	If the Current Activity is not the root of the activity tree Then	There is no activity logically 'previous' to the root of the activity tree.
4.2.1.	If the Sequencing Control Flow for the parent of the Current Activity is True And the Sequencing Control Forward Only for the parent of the Current Activity is False Then	Validate that a 'flow' sequencing request can be processed from the current activity.
4.2.1.1.	If the Activity is Active for the Current Activity is True Then	If the current activity has not been terminated, terminate the current the activity.
4.2.1.1.1.	Exit Navigation Request Process (Navigation Request: Valid; Termination Request: Exit; Sequencing Request: Previous; Target Activity: n/a)
4.2.1.2.	Else
4.2.1.2.1.	Exit Navigation Request Process (Navigation Request: Valid; Sequencing Request: Previous; Termination Request: n/a; Target Activity: n/a)
	End If
4.2.2.	Else
4.2.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)	Violates control mode.
	End If
4.3.	Else
4.3.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)	Cannot move backward from the root of the activity tree.
	End If
	End Case
5.	Case: navigation request is Forward	Behavior not defined.
5.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End Case
6.	Case: navigation request is Backward	Behavior not defined.
6.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End Case
7.	Case: navigation request is Choice
7.1.	If the activity specified by the Choice navigation request exists within the activity tree Then	Make sure the target activity exists in the activity tree.
7.1.1.	If the activity specified by the Choice navigation request is the root of the activity tree Or the Sequencing Control Choice for the parent of the activity specified by the Choice navigation request is True Then	Validate that a 'choice' sequencing request can be processed on the target activity.
7.1.1.1.	Find the common ancestor of the Current Activity and the activity specified by the Choice navigation request
7.1.1.2.	Form the activity path as the ordered series of activities from the Current Activity to the common ancestor, excluding the common ancestor.	The common ancestor will not terminate as a result of processing the choice sequencing request.
7.1.1.3.	If the activity path is Not Empty Then
7.1.1.3.1.	For each activity in the activity path	Make sure that 'choosing' the target will not force an active activity to terminate, if that activity does not allow choice to terminate it.
7.1.1.3.1.1.	If the Activity is Active for the activity is True And the Sequencing Control Choice Exit for the activity is False Then
7.1.1.3.1.1.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)	Violates control mode.
	End If
	End For
7.1.1.4.	End If
7.1.1.4.1.	If the Activity is Active for the Current Activity is True Then	If the current activity has not been terminated, terminate the current the activity.
7.1.1.4.1.1.	Exit Navigation Request Process (Navigation Request: Valid; Termination Request: Exit; Sequencing Request: Choice; Target Activity: the activity specified by the Choice navigation request)
7.1.1.4.2.	Else
7.1.1.4.2.1.	Exit Navigation Request Process (Navigation Request: Valid; Sequencing Request: Choice; Termination Request: n/a; Target Activity: the activity specified by the Choice navigation request)
	End If
7.1.2.	Else
7.1.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)	Violates control mode.
	End If
7.2.	Else
7.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)	Target activity does not exist.
	End If
	End Case
8.	Case: navigation request is Exit
8.1.	If the Current Activity is Defined Then	Make sure the sequencing session has already begun.
8.1.1.	If the Activity is Active for the Current Activity is True Then	Make sure the current activity has not already been terminated.
8.1.1.1.	Exit Navigation Request Process (Navigation Request: Valid; Termination Request: Exit; Sequencing Request: Exit; Target Activity: n/a)
8.1.2.	Else
8.1.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)	Activity has already terminated.
	End If
8.2.	Else
8.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End If
	End Case
9.	Case: navigation request is Exit All
9.1.	If the Current Activity is Defined Then	If the sequencing session has already begun, unconditionally terminate all active activities.
9.1.1.	Exit Navigation Request Process (Navigation Request: Valid; Termination Request: Exit All; Sequencing Request: Exit; Target Activity: n/a)
9.2.	Else
9.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End If
	End Case
10.	Case: navigation request is Abandon
10.1.	If the Current Activity is Defined Then	Make sure the sequencing session has already begun.
10.1.1.	If the Activity is Active for the Current Activity is True Then	Make sure the current activity has not already been terminated.
10.1.1.1.	Exit Navigation Request Process (Navigation Request: Valid; Termination Request: Abandon; Sequencing Request: Exit; Target Activity: n/a)
10.1.2.	Else
10.1.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End If
10.2.	Else
10.2.1	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End If
	End Case
11.	Case: navigation request is Abandon All
11.1	If the Current Activity is Defined Then	If the sequencing session has already begun, unconditionally abandon all active activities.
11.1.1.	Exit Navigation Request Process (Navigation Request: Valid; Termination Request: Abandon All; Sequencing Request: Exit; Target Activity: n/a)
11.2.	Else
11.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End If
	End Case
12.	Case: navigation request is Suspend All
12.1.	If the Current Activity is Defined Then	If the sequencing session has already begun.
12.1.1.	Exit Navigation Request Process (Navigation Request: Valid; Termination Request: Suspend All; Sequencing Request: Exit; Target Activity: n/a)
12.2.	Else
12.2.1.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)
	End If
	End Case
13.	Exit Navigation Request Process (Navigation Request: Not Valid; Sequencing Request: n/a; Termination Request: n/a; Target Activity: n/a)	Undefined navigation request.

TB.   Termination Behavior Model

The Simple Sequencing process delivers activities and tracks the current activity and other activities that have been attempted but not completed. Activities finish or are terminated due to other events and requests. When the activity finishes, the triggering event may imply that one or more other activities must also terminate or exit. Upon termination, post condition sequencing rules may imply that a pending sequencing request is replaced by the sequencing request specified in the sequencing rule. The process of evaluating exit action and post condition sequencing rules, recording information about the state of the activity when it finishes, and terminating other activities based on the defined sequencing behaviors is called the "termination process".

The termination process makes no assumptions as to how or when a termination request is generated.

The overall sequencing process (see Overall Sequencing Process OP) relates the termination process to the navigation, sequencing, rollup, selection and randomization, and delivery processes.

The termination process is controlled by parts of the sequencing definition model:

• Sequencing Rule Definitions - rules that when applied to an activity are used to specify sequencing behaviors for the activity.

The termination process uses parts of the tracking model:

• Objective Information - information about the results of the learner's interactions related to an objective.
• Progress Information - information about a learner's attempt at an activity.

The termination process uses data from the activity state model:

• Activity State Information - information about the results of the learner's state for an activity.

The behavior of the termination process is defined in terms of three process and two associated subprocesses:

• Termination Request Process - processes the termination request on the Current Activity (AM.1.2).
• End Attempt Process (UP.4) - processes completion data when the sequencing engine, not content objects, controls completion, and ends the current attempt on the activity.
• Overall Rollup Process - propagates state information (see Tracking Model TM) from Current Activity (AM.1.2) to its ancestors.
• Sequencing Exit Action Rules Subprocess - evaluates Exit action sequencing rules when an activity terminates and may identify an exiting ancestor.
• Sequencing Post Condition Rules Subprocess - evaluates Post Condition sequencing rules when an non-suspended activity terminates and may identify a sequencing request.

TB.1   Termination Requests

The termination process responds to one of a set of different termination requests. A termination request defines the actions to be performed when the request is processed. The request names are tokens in a vocabulary. The names have no semantics or meanings themselves. The definition of the action is the complete definition of the required behavior.

Termination Request	Action
Exit	The current attempt on the Current Activity (AM.1.2) is terminated normally; the attempt is over.
Exit All	The current attempts on all active activities (from the root to the Current Activity (AM.1.2), inclusive) are terminated normally; the attempts are over.
Suspend All	The current attempts on all active activities (from the root to the Current Activity (AM.1.2), inclusive) are suspended. The attempt on the Current Activity (AM.1.2) may be resumed.
Abandon	The current attempt on the Current Activity (AM.1.2) is terminated abnormally; the activity is not complete. The attempt may not be resumed. There is no rollback of any tracking data.
Abandon All	The current attempts on all active activities (from the root to the Current Activity (AM.1.2), inclusive) are terminated abnormally; the activities are not complete. Attempts on any abandoned activity may not be resumed. There is no rollback of any tracking data.

TB.2   Termination Behavior

The termination behavior describes how a termination request is processed. It marks attempts on activities as ended, updates the state of the activity tree, processes exit action and post condition sequencing rules, and may identify an alternative sequencing request.

An implementation must be capable of representing the processes described and have the implemented process exhibit the behavior described. There are no additional requirements on implementing the termination behavior model.

The termination behavior relies on the data descriptions from the sequencing definition model (see Sequencing Definition Model SM), the tracking model (see Tracking Model TM), and the activity state model (see Activity State Model AM). These information models also specify default data values in the activity tree that govern the access to activity, tracking, or state data. Simple Sequencing does not specify how content can set the data values in the tracking model.

TB.2.1 Sequencing Exit Action Rules Subprocess

Exit action sequencing rules on the current activity's ancestors are evaluated when the attempt on the current activity ends. This rule evaluation may result in the identification of one and only one of the current activity's ancestors to also terminate. The current attempt on all descendents of the identified activity end.

Sequencing rule conditions are specified by the Sequencing Rule Definitions. Sequencing rules are evaluated using the Sequencing Rules Check Process (UP.2).

• This subprocess assumes that the Overall Rollup Process (RB.1.4) has completed. It evaluates only sequencing rules whose actions are defined as Exit Action rules (see SM 1.2 Sequencing Rule Description), for all ancestors of the current activity. Rules on each activity, beginning at the root of the sequencing tree, are evaluated in order. The subprocess stops at the first rule that evaluates to True. This subprocess may cause one and only one of the current activity's ancestors to terminate. If one of the current activity's ancestors terminates, all of its active descendents also terminate and that activity becomes the current activity. See Figures TB.1 and TB.2.

Figure TB.1 illustrates an activity tree for a sequencing session that is "in progress". The current activity and all of its ancestors are active - an attempt on them is in progress and durations are accumulating.

The current activity has been identified in a termination request and the Exit request process has been initiated, e.g., a navigation request triggered exit. The End Attempt Process (UP.4) is applied to the current activity and Rollup is performed to ensure the activity tree is properly updated.

When the Sequencing Exit Action Rules Subprocess is applied to the current activity, one and only one of its ancestors may terminate. The ancestor that terminates is the one closest to the root of the activity tree that has an Exit Action Rule that evaluates to True. For example, assume both the parent activity and the grandparent activity of the current activity have Exit Action Rules that evaluate to True; only the grandparent activity will terminate. When an ancestor of the current activity terminates, the Sequencing Exit Action Rules Subprocess will terminate the attempt on the ancestor and all of its active descendents by applying the Terminate Descendent Attempts Process (UP.3) and make the current activity the activity identified for exit. For the example described above, Figure TB.2 shows the activity tree after the Sequencing Exit Action Rules Subprocess has completed.

The Sequencing Exit Action Rules Subprocess evaluates sequencing rules for the ancestors of the current activity, and as a result, one of those activities may terminate.

The Sequencing Exit Action Rules Subprocess is specified by the following pseudo code. The pseudo code describes only the exit action rule processing. How this process is implemented or how information is encoded, stored, represented, or bound is outside the scope of this specification. The Sequencing Exit Action Rules Subprocess only describes the expected behavior that an implementation will exhibit.

Sequencing Exit Action Rules Subprocess (for the Current Activity; may change the Current Activity):
Reference: Section: Current Activity AM.1.2 End Attempt Process UP.4 Sequencing Rules Check Process UP.2 Sequencing Rule Description SM.2 Terminate Descendent Attempts Process UP.3
1.	Form the activity path as the ordered series of activities from the root of the activity tree to the parent of the Current Activity, inclusive
2.	Initialize exit target to Null
3.	For each activity in the activity path	Evaluate all exit rules along the active path, starting at the root of the activity tree.
3.1.	Apply the Sequencing Rules Check Process to the activity and the set of Exit actions
3.2.	If the Sequencing Rules Check Process does not return Nil Then
3.2.1.	Set the exit target to the activity	Stop at the first activity that has an exit rule evaluating to true.
3.2.2.	Break For
	End If
	End For
4.	If exit target is Not Null Then
4.1.	Apply the Terminate Descendent Attempts Process to the exit target	End the current attempt on all active descendents.
4.2.	Apply the End Attempt Process to the exit target	End the current attempt on the 'exiting' activity.
4.3.	Set the Current Activity to the exit target	Move the current activity to the activity that identified for termination.
	End If
5.	Exit Sequencing Exit Action Rules Subprocess

TB.2.2   Sequencing Post Condition Rules Subprocess

Post condition sequencing rules are applied to the current activity when it terminates, if the current activity was not suspended. These sequencing rules may override the sequencing request generated from a navigation request or produce an additional termination request. The Sequencing Post Condition Rules Subprocess evaluates post condition sequencing rules on the current activity and may identify a termination or sequencing request.

Sequencing rule conditions are specified by the Sequencing Rule Definitions. Sequencing rules are evaluated using the Sequencing Rules Check Process (UP.2).

• This subprocess assumes the Sequencing Exit Action Rules Subprocess has completed, so that the Current Activity (AM.1.2) is accurate, given the current state of the activity tree. It evaluates only sequencing rules whose actions are defined as Post Condition rules (see SM 1.2 Sequencing Rule Description), on the current activity. Rules are only evaluated if the current activity was not suspended during its previous attempt. The subprocess stops at the first rule that evaluates to True and may return a termination and sequencing request.

The Sequencing Post Condition Rules Subprocess evaluates sequencing rules for the identified activity and may optionally return one and only one termination request and one and only one sequencing request, determined by the rule action.

The Sequencing Post Condition Rules Subprocess is specified by the following pseudo code. The pseudo code describes only the post condition rule processing. How this process is implemented or how information is encoded, stored, represented, or bound is outside the scope of this specification. The Sequencing Post Condition Rules Subprocess only describes the expected behavior that an implementation will exhibit.

Sequencing Post Condition Rules Subprocess (for the Current Activity; may return a termination request and a sequencing request):
Reference: Section: Activity is Suspended AM.1.1 Current Activity AM.1.2 Sequencing Rules Check Process UP.2 Sequencing Rule Description SM.2
1.	If Activity is Suspended for the Current Activity is True Then	Do not apply post condition rules to a suspended activity.
1.1.	Exit Sequencing Post Condition Rules Subprocess
	End If
2.	Apply the Sequencing Rules Check Process to the Current Activity and the set of Post Condition actions	Apply the post condition rules to the current activity.
3.	If the Sequencing Rules Check Process does not return Nil Then
3.1.	If the Sequencing Rules Check Process returned Retry, Continue, Or Previous Then
3.1.1.	Exit Sequencing Post Condition Rules Subprocess (Sequencing Request: the value returned by the Sequencing Rules Check Process; Termination Request: n/a)	Attempt to override any pending sequencing request with this one.
	End If
3.2.	If the Sequencing Rules Check Process returned Exit Parent Or Exit All Then
3.2.1.	Exit Sequencing Post Condition Rules Subprocess (Sequencing Request: n/a; Termination Request: the value returned by the Sequencing Rules Check Process)	Terminate the appropriate activity(s)
	End If
3.3.	If the Sequencing Rules Check Process returned Retry All Then
3.3.1.	Exit Sequencing Post Condition Rules Subprocess (Termination Request: Exit All; Sequencing Request: Retry)	Terminate all active activities and move the current activity to the root of the activity tree; then perform an 'in-process' start.
	End If
	End If
4.	Exit Sequencing Post Condition Rules Subprocess

TB.2.3   Termination Request Process

The Termination Request Process processes the termination request.

The process uses the Overall Rollup Process (RB.1.4), the Sequencing Exit Action Rules Subprocess (TB.2.1), the Sequencing Post Condition Rules Subprocess (TB.2.2), and the End Attempt Process (UP.4). It updates values in the tracking model and the activity state model.

• A termination request results in the current attempt on the current activity ending and status information in the activity tree being updated (through the End Attempt Process and the Overall Rollup Process). The Sequencing Exit Action Rules Subprocess may cause certain ancestors of the current activity to also terminate. The Sequencing Post Condition Rule Subprocess evaluates post condition rules on the Current Activity (AM.1.2). The result of the Termination Request Process may identify a new sequencing request.

Certain termination requests (Suspend All, Abandon, and Abandon All) do not result in any tracking model status change to the current activity; the End Attempt Process is not invoked for these termination requests.

The Termination Request Process processes the termination request and optionally returns a new sequencing request.

The Termination Request Process for a termination request is specified by the following pseudo code. The pseudo code describes only the termination request processing. How this process is implemented or how information is encoded, stored, represented, or bound is outside the scope of this specification. The Termination Request Process only describes the expected behavior that an implementation will exhibit.

Termination Request Process (for a termination request, ends the current attempt on the Current Activity; returns the validity of the termination request; may return a sequencing request):
Reference: Section: Activity is Active AM.1.1 Activity is Suspended AM.1.1 Current Activity AM.1.2 End Attempt Process UP.4 Overall Rollup Process RB.1.4 Sequencing Exit Action Rules Subprocess TB.2.1 Sequencing Post Condition Rules Subprocess TB.2.2 Terminate Descendent Attempts Process UP.3
1.	If the Current Activity is Not Defined Then	If the sequencing session has not already begun, there is nothing to terminate.
1.1.	Exit Termination Request Process (Termination Request: Not Valid; Sequencing Request: n/a)
	End If
2.	If Activity is Active for the Current Activity is False Then	If the current activity has already been terminated, there is nothing to terminate.
2.1.	Exit Termination Request Process (Termination Request: Not Valid; Sequencing Request: n/a)
	End If
3.	Case: termination request is Exit
3.1.	Apply the End Attempt Process to the Current Activity	Ensure the state of the current activity is up to date.
3.2.	Apply the Overall Rollup Process to the Current Activity	Propagate the state of the current activity up the tree.
3.3.	Apply the Sequencing Exit Action Rules Subprocess to the Current Activity	Check if any of the current activity's ancestors need to terminate.
3.4.	Repeat
3.4.1.	Set the processed exit to False
3.4.2.	If the Current Activity is Not the root of the activity tree Then
3.4.2.1.	Apply the Sequencing Post Condition Rules Subprocess to the Current Activity
3.4.2.2.	If the Sequencing Post Condition Rule Subprocess returned a termination request of Exit All Then
3.4.2.2.1.	Change the termination request to Exit All
3.4.2.2.2.	Break to the next Case
	End If
3.4.2.3.	If the Sequencing Post Condition Rule Subprocess returned a termination request of Exit Parent Then	If we exit the parent of the current activity, move the current activity to the parent of the current activity.
3.4.2.3.1.	Set the Current Activity to the parent of the Current Activity
3.4.2.3.2.	Apply the End Attempt Process to the Current Activity (AM.1.2)
3.4.2.3.3.	Set processed exit to True	Need to evaluate post conditions on the new current activity.
	End If
	End If
3.5.	Until processed exit is False
3.6.	Exit Termination Request Process (Termination Request: Valid; Sequencing Request: is the sequencing request returned by the Sequencing Post Condition Rule Subprocess, if one exists, otherwise n/a)
	End Case
4.	Case: termination request is Exit All
4.1.	If Activity is Active for the Current Activity is True Then	Has the completion subprocess and rollup been applied to the current activity yet?
4.1.1.	Apply the End Attempt Process to the Current Activity
4.1.2.	Apply the Overall Rollup Process to the Current Activity
	End If
4.2.	Apply the Terminate Descendent Attempts Process to the root of the activity tree
4.3.	Apply the End Attempt Process to the root of the activity tree
4.4.	Set the Current Activity to the root of the activity tree	Move the current activity to the root of the activity tree.
4.5.	Exit Termination Request Process (Termination Request: Valid; Sequencing Request: is the sequencing request returned by the Sequencing Post Condition Rule Subprocess, if one exists, otherwise an Exit sequencing request)	Inform the sequencer that the sequencing session has ended.
	End Case
5.	Case: termination request is Suspend All
5.1	If the Activity is Active for the Current Activity is True Then	If the current activity is active, suspend it and all of its descendents.
5.1.1.	Set the Suspended Activity to the Current Activity
5.2.	Else
5.2.1.	If the Activity is Suspended for the Current Activity is False Then	The current activity has already terminated; check if it was suspended.
5.2.1.1.	If the Current Activity is not the root of the activity tree Then	Make sure the current activity is not the root of the activity tree.
5.2.1.1.1.	Set the Suspended Activity to the parent of the Current Activity
5.2.1.2.	Else
5.2.1.2.1.	Exit Termination Request Process (Termination Request: Not Valid; Sequencing Request: n/a)	Nothing to suspend.
	End If
	End If
	End If
5.3.	Form the activity path as the ordered series of all activities from the Suspended Activity to the root of the activity tree, inclusive
5.4.	If the activity path is Empty Then
5.4.1.	Exit Termination Request Process (Termination Request: Not Valid; Sequencing Request: n/a)	Nothing to suspend.
	End If
5.5.	For each activity in the activity path
5.5.1.	Set Activity is Active for the activity to False
5.5.2.	Set Activity is Suspended for the activity to True
	End For
5.6.	Set the Current Activity to the root of the activity tree	Move the current activity to the root of the activity tree.
5.7.	Exit Termination Request Process (Termination Request: Valid; Sequencing Request: Exit)	Inform the sequencer that the sequencing session has ended.
	End Case
6.	Case: termination request is Abandon
6.1.	Set Activity is Active for the Current Activity to False
6.2.	Exit Termination Request Process (Termination Request: Valid; Sequencing Request: n/a)
	End Case
7.	Case: termination request is Abandon All
7.1.	Form the activity path as the ordered series of all activities from the Current Activity to the root of the activity tree, inclusive
7.2.	If the activity path is Empty Then
7.2.1.	Exit Termination Request Process (Termination Request: Not Valid; Sequencing Request: n/a)	Nothing to abandon.
	End If
7.3.	For each activity in the activity path
7.3.1.	Set Activity is Active for the activity to False
	End For
7.4.	Set the Current Activity to the root of the activity tree	Move the current activity to the root of the activity tree.
7.5.	Exit Termination Request Process (Termination Request: Valid; Sequencing Request: Exit)	Inform the sequencer that the sequencing session has ended.
	End Case
8.	Exit Termination Request Process (Termination Request: Not Valid; Sequencing Request: n/a)	Undefined termination request.