The SEDRIS Data Representation Model
APPENDIX B - Constraints
Precedence of Property Set Index

Definition

Consider an instance P of <Geometry Representation> or <Feature Representation>, where P has a <Property Set Index> component X that references a <Property Set> instance S.

Rationale

Objects contained directly by <Geometry Representation> or <Feature Representation> instances are more closely related to the <Geometry Representation> or <Feature Representation> instances than those contained in a <Property Set> instance; they will be specific while those in a <Property Set> instance will be more generic.

The order of the list of <Property Set Index> instances implies an order of precedence.

Example

  1. A <Feature Representation> instance contains a <Data Quality> instance with fictional set to SE_TRUE. It also references a <Property Set> instance that contains a <Data Quality> instance with fictional set to SE_FALSE. As a <Feature Representation> instance may have only one <Data Quality> component, the <Data Quality> instance with fictional set to SE_TRUE is used, as it is contained directly by the <Feature Representation> instance.

  2. A <Geometry Representation> instance contains two <Property Table Reference> instances and references a <Property Set> instance that contains another three. As a <Geometry Representation> instance may contain many <Property Table Reference> instances, all five are used by the <Geometry Representation> instance as required. The two that are contained directly are used first, then the three that are contained in the <Property Set> instance.

  3. Consider a <Geometry Representation> instance that has two <Image Mapping Function> components and references a <Property Set> instance that contains another two. As a <Geometry Representation> instance may contain many ordered <Image Mapping Function> instances, all four are used by the <Geometry Representation> instance as required. The two that are contained directly are used in order first, then the three that are contained in the <Property Set> instance, again in order.

  4. Consider a <Geometry Representation> instance that contains two <Property Table Reference> components and references two <Property Set> instances. The first <Property Set> instance contains another <Property Table Reference> instance and the second <Property Set> instance contains another three <Property Table Reference> instances. As a <Geometry Representation> instance may contain many <Property Table Reference> instances, all six are used by the <Geometry Representation> instance as required. The two that are contained directly are used first, then that contained in the first <Property Set> instance, and finally the three that are contained in the second <Property Set> instance.

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