Class

• <DRM Hierarchy Summary Item>

Superclass

• <DRM Base Summary Item>

Subclass

• None.

Definition

An instance of this DRM class represents an instance, or a number of identical instances, of a <DRM Geometry Hierarchy> or <DRM Feature Hierarchy> that exists within the given <DRM Model> or <DRM Environment Root> instance. <DRM Hierarchy Summary Item> instances are combined together to form hierarchies that mirror those that they summarize. This summary is a compressed form of the actual hierarchy, as each <DRM Hierarchy Summary Item> may represent a number of instances of the class indicated by its drm_class field.

Consequently, the multiplicity field records how many of the given class a <DRM Hierarchy Summary Item> actually represents. Note that all instances represented by one <DRM Hierarchy Summary Item> shall have exactly the same hierarchical pattern beneath them, right down to where the hierarchy summary concludes. In essence, a <DRM Hierarchy Summary Item> represents both the instance(s) that it describes, and the specific hierarchy beneath it (them); it may have an optional association to the <DRM Geometry Hierarchy(ies)> or <DRM Feature Hierarchy(ies)> that it summarizes.

Each <DRM Hierarchy Summary Item> (i.e. each object type) can optionally have a list of <DRM EDCS Use Summary Items> giving the classifications that are attached to those instances in the transmittal.

The Hierarchy Summary does not have to be a total representation of the entire transmittal hierarchy and can be limited to a useful high level summary.

If the producer of the transmittal deems it of potential use to consumers, the branches of the Hierarchy Summary can terminate with a list of <DRM DRM Class Summary Item> instances representing the objects beneath that point in the hierarchy.

Class diagram

Figure 6.123 — DRM_Hierarchy_Summary_Item

Constraints

• Hierarchy summary constraints
• Non crossing associations
• Non overlapping DRM Class Summary Items
• Publishable Object

Example(s)

• Consider an <DRM Environment Root> instance for which the geometry is to be summarized.

  

  Figure 6.124 — <DRM Hierarchy Summary Item> example

  The geometry portion of the above <DRM Environment Root> can therefore summarized as follows. Note that this is the same <DRM Environment Root> instance as shown above, but for readability only the <DRM Hierarchy Summary Item> portion of its instance diagram is shown here.

  

  Figure 6.125 — <DRM Hierarchy Summary Item> example

  The <DRM Hierarchy Summary Item> tree, rooted at the <DRM Environment Root>, parallels the structure of the corresponding geometry. In this instance, the data provider has elected not to provide a detailed summary of the <DRM Union Of Geometry Hierarchy>'s structure. The list of <DRM DRM Class Summary Item> components merely identify classes that are somewhere below the <DRM Union Of Geometry Hierarchy>, rather than the patterns in which they appear.

  The <DRM EDCS Use Summary Item> components summarize patterns of EDCS Classification Codes, possibly used together with EDCS Attribute Codes, in the context being summarized.

  If the data provider wished to summarize the hierarchy of the <DRM Union Of Geometry Hierarchy> in detail, its <DRM Hierarchy Summary Item> could be provided with appropriate <DRM Hierarchy Summary Item> components as desired, until the summary reached the level of <DRM Primitive Geometry> and the hierarchy summary came to an end.

  For examples of summaries of <DRM Primitive Geometry> patterns, see <DRM Primitive Summary Item>.