User-defined geometry property types

232 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 21.5.2 User-defined topology types and topology property types 21.5.2.1 User-defined topology types Authors of application schemas may create their own topology types if GML lacks the desired construct. To do this, authors shall ensure that the object elements of these concrete topology types are in the substitution group either directly or indirectly of the corresponding GML object element: gml:AbstractTopology. Any user-defined topology subtypes shall inherit the elements and attributes of the base GML topology types without restriction, but may extend these base types to meet application requirements, such as providing a finer degree of interoperability with legacy systems and data sets. All rules specified in Clauses 7 and 13 shall be followed.

21.5.2.2 User-defined topology property types

Furthermore, authors of application schemas may create their own directed topology property types that encapsulate topology types they have defined in accordance with Clause 13. They shall ensure that these properties follow the rules described in 21.2.6. In addition, the target type shall be a bona fide topology construct. A topology property type may be a restriction of an existing topology property type. A topology property type may support the choice between an inline or a by-reference semantic or it may restrict the use to either inline prohibit the use of the Xlink attributes or by-reference prohibit the containment of the geometry in the feature.

21.6 Schemas defining time

21.6.1 Import GML temporal schema components

The application schema shall import the GML schema as described in 21.2.3. Any GML profile referenced from the application schema shall include at least the gml:AbstractTimeObject element and all schema components used by this element. NOTE Typically additional temporal schema components are required besides those required by gml:AbstractTimeObject. In practice, especially concrete elements and types like gml:TimeInstant and gml:TimeInstantPropertyType will typically be part of the profile. 21.6.2 User-defined temporal types and temporal property types 21.6.2.1 User-defined temporal types Authors of application schemas may create their own temporal types if GML lacks the desired construct. To do this, authors shall ensure that the object elements of these concrete temporal types are in the substitution group either directly or indirectly of the corresponding GML object element: gml:AbstractTimeObject. Any user-defined temporal subtype shall inherit the elements and attributes of the base GML temporal types without restriction, but may extend these base types to meet application requirements, such as providing a finer degree of interoperability with legacy systems and data sets. All rules specified in Clauses 7 and 14 shall be followed.