Definition

1. A <Hierarchy Summary Item> instance shall have a drm_class field value corresponding to either:

   • the <Feature Hierarchy> class or one of its subclasses
   • the <Geometry Hierarchy> class or one of its subclasses

2. For any <Hierarchy Summary Item> instance B that is a component of another <Hierarchy Summary Item> instance A, the class represented by the drm_class field value of B shall be defined as a formal component of A, and the multiplicity and multiplicity_meaning of B shall comply with the corresponding component relationship between the two classes.

3. Consider an <Environment Root> instance ER.

   1. If ER has a <Geometry Hierarchy> component GH, ER shall have at most one <Hierarchy Summary Item> component HS_G for which the drm_class field corresponds to a <Geometry Hierarchy> subclass. If such a component instance HS_G exists, its field values shall comply with the following constraints.

      1. The drm_class field of HS_G shall match the DRM class of GH.

      2. The multiplicity_meaning of HS_G shall be SE_HSMULCOD_EXACT, and its multiplicity shall be 1.

   2. If ER does not have a <Geometry Hierarchy> component, ER shall not have any <Hierarchy Summary Item> component for which the drm_class field corresponds to a <Geometry Hierarchy> subclass.

   3. If ER has a <Feature Hierarchy> component FH, ER shall have at most one <Hierarchy Summary Item> component HS_F for which the drm_class field corresponds to a <Feature Hierarchy> subclass. If such a component instance HS_F exists, its field values shall comply with the following constraints.

      1. The drm_class of HS_F shall match the DRM class of FH.

      2. The multiplicity_meaning of HS_F shall be SE_HSMULCOD_EXACT, and its multiplicity shall be 1.

   4. If ER does not have a <Feature Hierarchy> component, ER shall not have any <Hierarchy Summary Item> component for which the drm_class field corresponds to a <Feature Hierarchy> subclass.

4. Consider a <Model> instance M.

   1. If M has a <Geometry Model> component with a <Geometry Hierarchy> component GH, M shall have at most one <Hierarchy Summary Item> component HS_G for which the drm_class field corresponds to a <Geometry Hierarchy> subclass. If such a component instance HS_G exists, its field values shall comply with the following constraints.

      1. The drm_class field of HS_G shall match the DRM class of GH.

      2. The multiplicity_meaning of HS_G shall be SE_HSMULCOD_EXACT, and its multiplicity shall be 1.

   2. If M does not have a <Geometry Model> component, or if the <Geometry Model> component of M does not have a <Geometry Hierarchy> component, M shall not have any <Hierarchy Summary Item> component for which the drm_class field corresponds to a <Geometry Hierarchy> subclass.

   3. If M has a <Feature Model> component with a <Feature Hierarchy> component FH, M shall have at most one <Hierarchy Summary Item> component HS_F for which the drm_class field corresponds to a <Feature Hierarchy> subclass. If such a component instance HS_F exists, its field values shall comply with the following constraints.

      1. The drm_class field of HS_F shall match the DRM class of FH.

      2. The multiplicity_meaning of HS_F shall be SE_HSMULCOD_EXACT, and its multiplicity shall be 1.

   4. If M does not have a <Feature Model> component, or if the <Feature Model> component of M does not have a <Feature Hierarchy> component, M shall not have any <Hierarchy Summary Item> component for which the drm_class field corresponds to a <Feature Hierarchy> subclass.

5. All <Geometry Hierarchy> instances (or <Feature Hierarchy> instances) associated with a given <Hierarchy Summary Item> instance shall be instances of the class specified by its drm_class field value, and shall conform to the structure that it specifies.

Rationale

A <Hierarchy Summary Item> component of an <Environment Root> instance or <Model> instance exists to summarize a corresponding hierarchy of its aggregate. Consequently, its drm_class and multiplicity shall be consistent with the hierarchy which it represents.

Example

No example supplied.

FAQs

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