Definition

<Geometry Representation> or <Feature Representation> instances may contain attribute and / or meta data objects and also <Property Set Index> instances that refer to <Property Sets>. If there is a clash between the attribute or meta data objects that are contained by the <Geometry Representation> or <Feature Representation> and any attribute or meta data objects that are contained by <Property Sets>, then objects contained directly by <Geometry Representation> or <Feature Representation> take precedence.

<Geometry Representation> and <Feature Representation> may contain an ordered list of <Property Set Index> instances. If a <Geometry Representation> or <Feature Representation> contains references to more than one <Property Set> and there is a clash between the attribute objects they contain, then attribute objects contained in <Property Sets> referenced first in this ordered list have precedence over those contained in <Property Sets> that are referenced later.

Precedence will behave differently depending on the multiplicity of the relationship that the attribute or meta data object in question has with the containing <Geometry Representation> or <Feature Representation>. In the event of a clash, the following rules will apply based on this enumeration.

• Zero or one:
  The object contained directly by the <Geometry Representation> or <Feature Representation> is used. If the clash is between objects in <Property Sets>, then the object contained in the <Property Set> that is referenced earliest in the list of <Property Set Index> instances is used.
• Zero or more:
  Those contained directly by the <Geometry Representation> or <Feature Representation> are used, followed by those contained in the <Property Sets>, in the order that the <Property Sets> are referenced by the <Geometry Representation> or <Feature Representation>.
• Zero or more {ordered}:Those contained directly by the <Geometry Representation> or <Feature Representation> are used in order. Those contained in the <Property Set> referenced by the first <Property Set Index> instance in the list are then used, in order. Then those contained in the <Property Set> referenced by the second <Property Set Index> instance in the list, in order.

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 would be used by the <Geometry Representation> instance as required. The two that are contained directly would be 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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