Table 6

Table 6.207—DRM_Primitive_Summary_Item

Property

Description

Superclass

· <DRM Base Summary Item>

Class

· <DRM Primitive Summary Item>

Subclass

· none

Definition

An object of this DRM class specifies common patterns of primitive objects that appear in a <DRM Model> or under <DRM Environment Root>. Each <DRM Primitive Summary Item> represents one or more instances of the class specified by its drm_class field that conform to the specified pattern.

<DRM Primitive Summary Item>s can only represent objects of the <DRM Primitive Geometry> and <DRM Primitive Feature> classes and subclasses, and also the classes that may come beneath them in the hierarchy. Instances are combined to form a hierarchy that mirrors the hierarchy of the primitive instances that the <DRM Primitive Summary Item> represent, such that The summary is a compressed form of the actual hierarchy.

Since a <DRM Primitive Summary Item> instance may represent many instances of the primitive that it summarizes, it has a multiplicity field, indicating how many instances of the pattern it represents. All instances represented by a given <DRM Primitive Summary Item> shall conform exactly to that pattern, up to the point where the summary's pattern ceases to provide specifics.

Example(s)

· Summary of a common <DRM Polygon> structure pattern within a <DRM Model>. In this case, the pattern indicates that we can expect to see triangles. Note that other patterns can be present; in this particular example, the <DRM Model> contains not only triangles, but other types of <DRM Polygon>s, such as quadrilaterals and even five-sided <DRM Polygon>s. The <DRM Primitive Summary Item> are just indicating common patterns; they're not enumerating all the patterns that are present.