ValueArray Value objects schema

190 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. members are homogeneous, the gml:referenceSystem uom, codeSpace may be specified on the gml:ValueArray itself and inherited by all the members if desired. EXAMPLE 1 The gml:ValueArray element may appear in instances as follows. In the first example a set of points are each the value of a gml:valueComponent property. One of the values is provided by-reference, using the standard xlink:href syntax: gml:ValueArray gml:valueComponent gml:Point srsName=urn:x-ogc:def:crs:EPSG:6.6:63266405 gml:pos-32. 71.gml:pos gml:Point gml:valueComponent gml:valueComponent gml:Point srsName=urn:x-ogc:def:crs:EPSG:6.6:63266405 gml:pos-35. 70.gml:pos gml:Point gml:valueComponent gml:valueComponent xlink:href=http:my.big.orglocationspointspoint456 gml:ValueArray EXAMPLE 2 In the second example a set of quantities are contained within a gml:valueComponents property. One of the values is not available, indicated by a nil value: gml:ValueArray gml:valueComponents gml:Quantity uom=C21.gml:Quantity gml:Quantity uom=C37.gml:Quantity gml:Quantity xsi:nil=true nilReason=‖missing‖ gml:valueComponents gml:ValueArray EXAMPLE 3 Note that a gml:AbstractScalarValueList is usually preferred for arrays of scalar values since this is a more efficient encoding. The information in the previous example may be expressed: gml:QuantityList uom=C21. 37. missinggml:QuantityList However, if the values of the components are not scalars, then the explicit form is required.

16.4.12 Typed ValueExtents: CategoryExtent, CountExtent, QuantityExtent

Three elements are provided for typed value extents, for categories, counts and quantities. Their content models are defined by restricting the relevant scalar list types to contain exactly two items as follows: element name=CategoryExtent type=gml:CategoryExtentType substitutionGroup=gml:AbstractValue complexType name=CategoryExtentType simpleContent restriction base=gml:CodeOrNilReasonListType length value=2 restriction simpleContent complexType element name=CountExtent type=gml:CountExtentType substitutionGroup=gml:AbstractValue simpleType name=CountExtentType restriction base=gml:integerOrNilReasonList length value=2 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 191 restriction simpleType element name=QuantityExtent type=gml:QuantityExtentType substitutionGroup=gml:AbstractValue complexType name=QuantityExtentType simpleContent restriction base=gml:MeasureOrNilReasonListType length value=2 restriction simpleContent complexType A gml:QuantityExtent element or another element using this type will contain two values and a scale. EXAMPLE 1 gml:QuantityExtent uom=‖mm‖0. 9.5gml:QuantityExtent An element of gml:CategoryExtentType is useful if the codeSpace defines a set of ordered terms. EXAMPLE 2 my:AgeRange codeSpace=‖http:iugg.orggeologicalPeriods‖Cambrian Devonianmy:AgeRange Any value extent may describe a single-ended interval by using a NilReason value for one of the limits. EXAMPLE 3 gml:CountExtent53 inapplicablegml:CountExtent describes the integers starting with 53.

16.4.13 BooleanPropertyType, CategoryPropertyType, CountPropertyType, QuantityPropertyType

A set of convenience types gml:BooleanPropertyType, gml:CategoryPropertyType, gml:CountPropertyType, gml:QuantityPropertyType are provided for properties whose content is a specific member of the gml:AbstractScalarValue substitution group. Their definitions follow the same pattern, as exemplified by the definition of gml:BooleanPropertyType: complexType name=BooleanPropertyType sequence minOccurs=0 element ref=gml:Boolean sequence attributeGroup ref=gml:AssociationAttributeGroup complexType 17 GML schema — Directions

17.1 Direction schema

The direction schema components provide the GML application schema developer with a standard property element to describe direction, and associated objects that may be used to express orientation, direction, heading, bearing or other directional aspects of geographic features. NOTE The corresponding schema document is identified by the following location-independent name using URN syntax: urn:x-ogc:specification:gml:schema-xsd:direction:3.2.1

17.2 direction, DirectionPropertyType

The property gml:direction is intended as a predefined property expressing a direction to be assigned to features defined in a GML application schema. It is declared as follows: