AbstractGeneralOperationParameterPropertyType OperationParameter OperationParameterPropertyType OperationParameterGroup

Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 137 complexContent extension base=gml:AbstractGeneralOperationParameterType sequence element ref=gml:maximumOccurs minOccurs=0 element ref=gml:parameter minOccurs=2 maxOccurs=unbounded sequence extension complexContent complexType gml:OperationParameterGroup is the definition of a group of parameters used by an operation method. This complex type is expected to be used or extended for all applicable operation methods, without defining operation- method-specialized element names. The gml:parameter elements are an unordered list of associations to the set of operation parameters that are members of this group.

12.6.6.7 maximumOccurs

element name=maximumOccurs type=positiveInteger gml:maximumOccurs is the maximum number of times that values for this parameter group may be included. If this attribute is omitted, the maximum number shall be one.

12.6.6.8 OperationParameterPropertyType

complexType name=OperationParameterGroupPropertyType sequence minOccurs=0 element ref=gml:OperationParameterGroup sequence attributeGroup ref=gml:AssociationAttributeGroup complexType gml:OperationParameterPropertyType is a property type for association roles to an operation parameter group, either referencing or containing the definition of that parameter group. 13 GML schema — Topology

13.1 General concepts

13.1.1 Overview

Topology is the branch of mathematics describing the properties of objects which are invariant under continuous deformation. For example, a circle is topologically equivalent to an ellipse because one can be transformed into the other by stretching. In geographic modelling, the foremost use of topology is in accelerating computational geometry. The constructs of topology allow characterization of the spatial relationships between objects using simple combinatorial or algebraic algorithms. Topology, realized by the appropriate geometry, also allows a compact and unambiguous mechanism for expressing shared geometry among geographic features. NOTE 1 The topology model of GML complies with ISO 19107. The underlying concepts of the types and elements of the GML topology model are discussed in this document in more detail. This clause describes the topology schema components as specified by GML. 138 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. NOTE 2 The corresponding topology schema document, topology.xsd see Annex C, is identified by the following location- independent name using URN syntax: urn:x-ogc:specification:gml:schema-xsd:topology:3.2.1 There are four instantiable classes of primitive topology objects, one for each dimension up to 3D. In addition, topology complexes are supported. There is strong symmetry in the topological boundary and coboundary relationships between topology primitives of adjacent dimensions. Topology primitives are bounded by directed primitives of one lower dimension. The coboundary of each topology primitive is formed from directed topology primitives of one higher dimension.

13.1.2 Relationship with ISO 19107

The spatial topology components of the GML schema specified in this clause provide a conformant, partial implementation of the ISO 19107 spatial schema topology. The relationship is discussed in detail in D.2.3. The ISO 19107 topology types implemented in GML are specified in ISO 19107; some additional constraints are specified in ISO 19107 for these types, which are also constraints on the spatial topology components of the GML schema. In addition, GML specifies complementary spatial topology schema components as described in D.3.10.

13.2 Abstract topology

complexType name=AbstractTopologyType abstract=true complexContent extension base=gml:AbstractGMLType complexContent complexType element name=AbstractTopology type=gml:AbstractTopologyType abstract=true substitutionGroup=gml:AbstractGML This abstract type supplies the root or base type for all topological elements including primitives and complexes. It inherits AbstractGMLType and hence can be identified using the gml:id attribute. gml:AbstractTopology implements ISO 19107 TP_Object see D.2.4.2 and ISO 19107:2003, 7.2.2.

13.3 Topological primitives

13.3.1 Abstract topological primitives 13.3.1.1 AbstractTopoPrimitive, AbstractTopoPrimtive complexType name=AbstractTopoPrimitiveType abstract=true complexContent extension base=gml:AbstractTopologyType sequence extension complexContent complexType element name=AbstractTopoPrimitive type=gml:AbstractTopoPrimitiveType abstract=true substitutionGroup=gml:AbstractTopology