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3.1. Sequencing Definition Model Overview
The SCORM Sequencing Definition Model is an information model derived from the IMS SS [1]. The IMS SS Sequencing Definition Model defines a set of elements that can be used to describe and affect various sequencing behaviors. In addition, several SCORM specific elements have been defined that provide extended, application profile specific, behaviors and restrictions beyond those currently defined by IMS SS.
The SCORM Sequencing Definition Model defines a set of elements that may be used by content developers to define intended sequencing behavior. The definition model elements are applied to learning activities within the context of an activity tree. Each element has a default value that is to be assumed by any sequencing implementation in the absence of an explicitly defined value. The effects of the SCORM Sequencing Definition Model elements only apply during the application of SCORM Sequencing Behaviors (refer to Section 4: Sequencing Behaviors). A SCORM compliant LMS must support the behaviors that result from the values associated with all of the defined Sequencing Definition Model elements, including both explicitly declared and default values. The normative sequencing behavior is detailed in the Sequencing Behavior Pseudo Code (refer to Appendix C).
SCORM does not require or imply that the values of sequencing definition model elements applied to an activity are, become or remain static for any period. So long as the value space of an element is adhered to, an LMS may alter the element’s value as it desires. However, some groups of sequencing definition model elements are highly coupled to one another through the SCORM Sequencing Behavior. It is strongly recommended that LMSs take great care when altering values of SCORM Sequencing Definition Model elements, especially during an active learner experience.
SCORM does not place any requirements on when or how SCORM Sequencing Definition Model elements are applied to learning activities. However, the SCORM CAM book [3] does describe how these elements are applied to a Content Organization included in a SCORM Content Package. As described in Section 2.1.1: Deriving an Activity Tree from a Content Package, it is recommended that SCORM Sequencing Definition Model elements be applied to activities in a derived activity tree when the Content Package is processed. This allows author time declaration of intended sequencing behaviors to be communicated through a content organization so that sequencing information can be interoperably transferred between systems using SCORM Content Packages.