Metadata gmlBase schema components
8.1 Xlinks — Object associations and remote properties
The normative Xlink specification is available from W3C. NOTE A schema document xlinks.xsd is provided as part of the GML schema documents in Annex C. Xlink components are used in GML to implement associations between objects by reference. GML property elements see 7.2.3 may carry Xlink attributes, which support the encoding of an association relationship by reference, the name of the property element denoting the target role in the association. The most important Xlink component is: xlink:href identifier of the resource which is the target of the association, given as a URI The appearance of an xlink:href on a GML property indicates that the value of the property shall be found by traversing the link, that is the value is pointed to by the value of the xlink:href attribute. Following the terminology of Xlink, GML properties with xlink:href attributes are sometimes referred to as remote properties. Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 35 The other Xlink components are used to indicate additional semantics of the relationship. The most useful of these are xlink:role description of the nature of the target resource, given as a URI xlink:arcrole description of the role or purpose of the target resource in relation to the present resource, given as a URI xlink:title description of the association or the target resource, given as text For complete definitions of these and other Xlink components, including their use in extended Xlink association maps, refer to the Xlink specification. A URI reference [URI] is defined as an optional choice between an absolute or relative URI, followed by fragment identifier that consists of a crosshatch and additional reference information. For GML object properties and remote associations, this additional reference information shall be one of the following: a shorthand formerly called barename XPointer [XPointer Framework] consisting of the value of the gml:id attribute of a GML object, or an element scheme based XPointer [XPointer element], or an xpointer scheme based XPointer [XPointer xpointer] containing an XPath [XPath] expression that selects a GML object, optionally preceded by one or more xmlns scheme based XPointers [XPointer xmlns] that define the namespace prefixes used in the XPath expression. A URI that does not contain an absolute or relative URI, but that consists entirely of a fragment identifier, refers to a GML object elsewhere in the same GML document. Absolute and relative URIs may include a query component that consists of a question mark ? followed by a query to be interpreted by the resource. For GML object properties and remote associations, any such query shall be a request to a service that returns a GML object. The URI containing such a query may or may not make use of a fragment identifier, depending on the request syntax defined by the service. In the GML schema, simple Xlinks are used exclusively to denote association roles of GML objects and to denote remotely referenced property values. EXAMPLE 1 A reference to an object element in the same GML document may be encoded as: myProperty xlink:href=o1 EXAMPLE 2 A reference to an object element in a remote XML document using the gml:id value of that object may be encoded as: myProperty xlink:href=http:my.big.orgtest.xmlo1 EXAMPLE 3 A reference to an object element in a remote XML document or GML object repository using the gml:identifier property value of that object may be encoded as: myProperty xlink:href=http:my.big.orgtest.xmlelement gml:GeodeticCRS[.gml:identifier[codeSpace=urn:x-ogc:def:crs:EPSG:6.3:]=4326] EXAMPLE 4 A reference to an object element with a uniform resource name may be encoded as follows note that a URN resolver is required to resolve the URN and access the referenced object: myProperty xlink:href=urn:x-ogc:def:crs:EPSG:6.3:4326Parts
» Conformance requirements Change Requests | OGC
» Conformance classes related to GML application schemas Conformance classes related to GML profiles
» application schema Terms and definitions
» composite solid Terms and definitions
» curve data type Terms and definitions
» face feature Terms and definitions
» GML application schema Terms and definitions
» rectified grid schema Terms and definitions
» tag XML Terms and definitions
» Symbols and abbreviated terms
» XML namespaces Versioning Change Requests | OGC
» Deprecated parts of previous versions of GML
» UML notation Change Requests | OGC
» GML application schemas Change Requests | OGC
» Organization of this International Standard
» Deprecated and experimental schema components
» GML instance documents GML model and syntax
» Lexical conventions GML model and syntax
» XML Schema definition of GML language
» Goals of base schema components
» AbstractGML, AbstractGMLType Base objects .1
» abstractAssociationRole, AssociationRoleType GML properties .1
» Ownership of property values
» abstractReference, ReferenceType GML properties .1
» abstractInlineProperty, InlinePropertyType GML properties .1
» Properties representing the same relationship
» description Standard properties of GML objects .1
» descriptionReference Standard properties of GML objects .1
» name, identifier Standard properties of GML objects .1
» id Standard properties of GML objects .1
» GML object collections, AggregationAttributeGroup
» Metadata gmlBase schema components
» Xlinks — Object associations and remote properties
» Elements declared to be “nillable”
» CodeType, CodeWithAuthorityType Simple types .1
» MeasureType, UomIdentifier Simple types .1
» General concepts Change Requests | OGC
» Relationship with ISO 19109 Change Requests | OGC
» boundedBy, BoundingShapeType, EnvelopeWithTimePeriod, EnvelopeWithTimePeriodType
» locationName, locationReference FeaturePropertyType, FeatureArrayPropertyType
» Geometry properties Change Requests | OGC
» Topology properties Temporal properties
» GML feature collections Feature collections
» AbstractFeatureMemberType and derived property types
» Relationship with ISO 19107 General concepts
» SRSReferenceGroup Abstract geometry .1 AbstractGeometryType
» SRSInformationGroup Abstract geometry .1 AbstractGeometryType
» AbstractGeometry Abstract geometry .1 AbstractGeometryType
» GeometryPropertyType GeometryArrayPropertyType Abstract geometry .1 AbstractGeometryType
» geometricPositionGroup Coordinate geometry, vectors and envelopes .1 DirectPositionType, pos
» geometricPositionListGroup Coordinate geometry, vectors and envelopes .1 DirectPositionType, pos
» VectorType, Vector Coordinate geometry, vectors and envelopes .1 DirectPositionType, pos
» EnvelopeType, Envelope Coordinate geometry, vectors and envelopes .1 DirectPositionType, pos
» AbstractGeometricPrimitiveType, AbstractGeometricPrimitive Abstract geometric primitives
» GeometricPrimitivePropertyType Abstract geometric primitives
» PointType, Point Geometric primitives 0-dimensional
» PointPropertyType, pointProperty Geometric primitives 0-dimensional
» PointArrayPropertyType, pointArrayProperty Geometric primitives 0-dimensional
» AbstractCurveType, AbstractCurve Geometric primitives 1-dimensional
» LineStringType, LineString Geometric primitives 1-dimensional
» CurveType, Curve Geometric primitives 1-dimensional
» OrientableCurveType, OrientableCurve, baseCurve Geometric primitives 1-dimensional
» ArcStringType, ArcString ArcType, Arc
» CircleType, Circle ArcStringByBulgeType, ArcStringByBulge
» ArcByBulgeType, ArcByBulge ArcByCenterPointType, ArcByCenterPoint
» CubicSplineType, CubicSpline Curve segments .1 AbstractCurveSegmentType, AbstractCurveSegment
» BSplineType, BSpline Curve segments .1 AbstractCurveSegmentType, AbstractCurveSegment
» KnotType, KnotPropertyType Curve segments .1 AbstractCurveSegmentType, AbstractCurveSegment
» KnotTypesType Curve segments .1 AbstractCurveSegmentType, AbstractCurveSegment
» BezierType, Bezier Curve segments .1 AbstractCurveSegmentType, AbstractCurveSegment
» ClothoidType, Clothoid Curve segments .1 AbstractCurveSegmentType, AbstractCurveSegment
» GeodesicType, Geodesic Curve segments .1 AbstractCurveSegmentType, AbstractCurveSegment
» SurfaceArrayPropertyType, surfaceArrayProperty Geometric primitives 2-dimensional
» AbstractRingType, AbstractRing AbstractRingPropertyType Geometric primitives 2-dimensional
» LinearRingType, LinearRing Geometric primitives 2-dimensional
» LinearRingPropertyType SurfaceType, Surface Geometric primitives 2-dimensional
» Ring, RingType, curveMember OrientableSurfaceType, OrientableSurface, baseSurface
» TriangulatedSurface TinType, Tin OrientableSurfaceType, OrientableSurface, baseSurface
» LineStringSegmentArrayPropertyType OrientableSurfaceType, OrientableSurface, baseSurface
» TriangleType, Triangle RectangleType, Rectangle
» ConeType, Cone Surface patches .1 AbstractSurfacePatchType, gml : AbstractSurfacePatch
» CylinderType, gmlCylinder Surface patches .1 AbstractSurfacePatchType, gml : AbstractSurfacePatch
» SphereType, Sphere Surface patches .1 AbstractSurfacePatchType, gml : AbstractSurfacePatch
» AbstractSolidType, AbstractSolid Geometric primitives 3-dimensional
» SolidPropertyType, solidProperty Geometric primitives 3-dimensional
» SolidArrayPropertyType, solidArrayProperty Geometric primitives 3-dimensional
» SolidType, Solid Geometric primitives 3-dimensional
» ShellType, Shell ShellPropertyType Geometric primitives 3-dimensional
» GeometricComplexPropertyType Geometric complex .1 GeometricComplexType, GeometricComplex
» Relationship with ISO 19111 Important XML elements
» domainOfValidity Abstract coordinate reference system .1 AbstractCRS
» scope CRSPropertyType Abstract coordinate reference system .1 AbstractCRS
» Overview Coordinate reference systems
» Conversion Abstract coordinate reference systems .1 AbstractSingleCRS
» EllipsoidalCS cartesianCS Concrete coordinate reference systems .1 CompoundCRS
» sphericalCS Concrete coordinate reference systems .1 CompoundCRS
» geodeticDatum Concrete coordinate reference systems .1 CompoundCRS
» GeodeticCRSPropertyType VerticalCRS Concrete coordinate reference systems .1 CompoundCRS
» VerticalCRSPropertyType ProjectedCRS Concrete coordinate reference systems .1 CompoundCRS
» baseCRS derivedCRSType Concrete coordinate reference systems .1 CompoundCRS
» EngineeringCRS cylindricalCS Concrete coordinate reference systems .1 CompoundCRS
» EngineeringCRSPropertyType ImageCRS Concrete coordinate reference systems .1 CompoundCRS
» ImageCRSPropertyType TemporalCRS timeCS Concrete coordinate reference systems .1 CompoundCRS
» temporalDatum Concrete coordinate reference systems .1 CompoundCRS
» TemporalCRSPropertyType Concrete coordinate reference systems .1 CompoundCRS
» axisAbbrev Coordinate system axes .1 CoordinateSystemAxis
» axisDirection Coordinate system axes .1 CoordinateSystemAxis
» minimumValue, maximumValue, rangeMeaning Coordinate system axes .1 CoordinateSystemAxis
» uom Coordinate system axes .1 CoordinateSystemAxis
» CoordinateSystemAxisPropertyType Coordinate system axes .1 CoordinateSystemAxis
» axis Abstract coordinate system .1 AbstractCoordinateSystem
» EllipsoidalCSPropertyType CartesianCS Concrete coordinate systems .1 EllipsoidalCS
» CartesianCSPropertyType Concrete coordinate systems .1 EllipsoidalCS
» VerticalCS Concrete coordinate systems .1 EllipsoidalCS
» VerticalCSPropertyType TimeCS TimeCSPropertyType Concrete coordinate systems .1 EllipsoidalCS
» UserDefinedCS Concrete coordinate systems .1 EllipsoidalCS
» UserDefinedCSPropertyType Concrete coordinate systems .1 EllipsoidalCS
» SphericalCS Concrete coordinate systems .1 EllipsoidalCS
» SphericalCSPropertyType PolarCS Concrete coordinate systems .1 EllipsoidalCS
» CylindricalCSPropertyType AffineCS Concrete coordinate systems .1 EllipsoidalCS
» AffineCSPropertyType Concrete coordinate systems .1 EllipsoidalCS
» primeMeridian ellipsoid Geodetic datum .1 GeodeticDatum
» GeodeticDatumPropertyType Geodetic datum .1 GeodeticDatum
» Ellipsoid, semiMajorAxis, secondDefiningParameter Geodetic datum .1 GeodeticDatum
» EllipsoidPropertyType Geodetic datum .1 GeodeticDatum
» PrimeMeridian, greenwichLongitude Geodetic datum .1 GeodeticDatum
» EngineeringDatumPropertyType ImageDatum Other concrete datums .1 EngineeringDatum
» VerticalDatum VerticalDatumPropertyType Other concrete datums .1 EngineeringDatum
» TemporalDatum, origin Other concrete datums .1 EngineeringDatum
» TemporalDatumPropertyType Other concrete datums .1 EngineeringDatum
» operationVersion coordinateOperationAccuracy sourceCRS targetCRS CoordinateOperationPropertyType
» AbstractSingleOperation Abstract coordinate operations .1 AbstractCoordinateOperation
» CoordOperation Concrete coordinate operations .1 ConcatenatedOperation
» Conversion method parameterValue Concrete coordinate operations .1 ConcatenatedOperation
» ConversionPropertyType Transformation Concrete coordinate operations .1 ConcatenatedOperation
» ParameterValue value Parameter values and groups .1 AbstractGeneralParameterValue
» stringValue integerValue Parameter values and groups .1 AbstractGeneralParameterValue
» booleanValue Parameter values and groups .1 AbstractGeneralParameterValue
» valueList Parameter values and groups .1 AbstractGeneralParameterValue
» integerValueList Parameter values and groups .1 AbstractGeneralParameterValue
» valueFile Parameter values and groups .1 AbstractGeneralParameterValue
» operationParameter Parameter values and groups .1 AbstractGeneralParameterValue
» ParameterValueGroup Parameter values and groups .1 AbstractGeneralParameterValue
» formula, formulaCitation Operation method .1 OperationMethod
» sourceDimensions Operation method .1 OperationMethod
» targetDimensions parameter Operation method .1 OperationMethod
» OperationMethodPropertyType Operation method .1 OperationMethod
» minimumOccurs Operation parameters and groups .1 GeneralOperationParameter
» maximumOccurs Operation parameters and groups .1 GeneralOperationParameter
» OperationParameterPropertyType Operation parameters and groups .1 GeneralOperationParameter
» Abstract topological primitives .1 AbstractTopoPrimitive, AbstractTopoPrimtive
» DirectedNodePropertyType, directedNode Topological primitives 0-dimensional .1 NodeType, Node
» DirectedEdgePropertyType, directedEdge Topological primitives 1-dimensional .1 EdgeType, Edge
» DirectedFacePropertyType, directedFace Topological primitives 2-dimensional .1 FaceType, Face
» TopoComplexType, TopoComplex Maximal, sub- and super-complexes
» TopoComplexPropertyType, topoComplexProperty Topology complex
» Relationship with ISO 19108 General concepts
» AbstractTimePrimitive Abstract temporal objects .1 AbstractTimeObject
» TimePrimitivePropertyType, validTime Abstract temporal objects .1 AbstractTimeObject
» RelatedTimeType AbstractTimeComplex Abstract temporal objects .1 AbstractTimeObject
» AbstractTimeGeometricPrimitive TimeInstant Temporal geometry .1 Introduction
» TimeInstantPropertyType TimePeriod Temporal geometry .1 Introduction
» TimePeriodPropertyType Temporal geometry .1 Introduction
» TimePositionType, timePosition Temporal geometry .1 Introduction
» timeLength, duration, timeInterval, TimeUnitType
» Introduction Temporal topology schema
» AbstractTimeTopologyPrimitive Temporal topology objects .1 Overview
» TimeTopologyPrimitivePropertyType TimeTopologyComplex Temporal topology objects .1 Overview
» TimeEdge Temporal topology objects .1 Overview
» TimeEdgePropertyType Temporal topology objects .1 Overview
» Overview Temporal reference systems
» Basic temporal reference system, TimeReferenceSystem TimeCoordinateSystem
» TimeCalendar, TimeCalendarEra Calendars and clocks .1 Overview
» TimeCalendarPropertyType, TimeCalendarEraPropertyType TimeClock Calendars and clocks .1 Overview
» TimeClockPropertyType Calendars and clocks .1 Overview
» TimeOrdinalReferenceSystem, TimeOrdinalEra Ordinal temporal reference systems .1 Overview
» TimeOrdinalEraPropertyType Ordinal temporal reference systems .1 Overview
» Overview dataSource Representing dynamic features
» Dynamic properties DynamicFeature DynamicFeatureCollection
» AbstractTimeSlice Representing dynamic features
» history Representing dynamic features
» Overview Abstract topology Overview
» Definition, DefinitionType, remarks Dictionary schema
» Dictionary, DictionaryType Dictionary schema
» dictionaryEntry, DictionaryEntryType Using definitions and dictionaries
» Introduction Change Requests | OGC
» Using unit definitions Units schema
» unitOfMeasure, UnitOfMeasureType Units schema
» UnitDefinition, UnitDefinitionType Units schema
» quantityType, quantityTypeReference Units schema
» BaseUnit, BaseUnitType, unitsSystem Units schema
» DerivedUnit, DerivedUnitType Units schema
» derivationUnitTerms, DerivationUnitTermType Units schema
» ConventionalUnit, ConventionalUnitType Units schema
» Example of units dictionary informative
» Scalar measure types Measures schema
» Introduction Value objects schema
» Value element hierarchy Value objects schema
» Boolean, BooleanList Value objects schema
» Category, CategoryList Value objects schema
» Count, CountList Value objects schema
» Quantity, QuantityList Value objects schema
» AbstractValue, AbstractScalarValue, AbstractScalarValueList Value
» valueProperty, valueComponent, valueComponents Value objects schema
» CompositeValue Value objects schema
» ValueArray Value objects schema
» Typed ValueExtents: CategoryExtent, CountExtent, QuantityExtent
» Direction schema direction, DirectionPropertyType
» DirectionVectorType DirectionDescriptionType Change Requests | OGC
» Overview Observation Observation schema
» using target Observation schema
» resultOf DirectedObservation Observation schema
» General remarks The coverage model and representations
» Formal description of a coverage
» Coverage in GML The coverage model and representations
» Relationship with ISO 19123 The coverage model and representations
» AbstractCoverageType, AbstractCoverage Coverage schema
» DiscreteCoverageType, AbstractDiscreteCoverage Coverage schema
» AbstractContinuousCoverageType, AbstractContinuousCoverage Coverage schema
» domainSet, DomainSetType Coverage schema
» rangeSet, RangeSetType DataBlock Coverage schema
» tupleList doubleOrNilReasonTupleList Coverage schema
» File, FileType Coverage schema
» coverageFunction, CoverageFunctionType Coverage schema
» CoverageMappingRule GridFunction, GridFunctionType Coverage schema
» sequenceRule, SequenceRuleType, SequenceRuleEnumeration Coverage schema
» MultiCurveCoverage MultiSurfaceCoverage Coverage schema
» MultiSolidCoverage GridCoverage Coverage schema
» Observations Profiles of GML and application schemas
» Definition of profile Change Requests | OGC
» Relation to application schema
» Rules for elements and types in a profile
» Rules for referencing GML profiles from application schemas
» Recommendations for application schemas using GML profiles
» Summary of rules for GML profiles
» GML documents Instances of GML objects
» Introduction GML application schemas
» Target namespace GML application schemas
» Import GML schema GML application schemas
» Object type derivation GML application schemas
» Elements representing objects GML application schemas
» Property type derivation GML application schemas
» Elements representing properties GML application schemas
» Introduction Import GML schema components
» Elements representing features Schemas defining Features and Feature Collections
» Application features are features
» User-defined geometry property types
» User-defined topology property types
» User-defined temporal property types
» Introduction Schemas defining coordinate reference systems
» Import GML coordinate reference system schema components
» Introduction Schemas defining coverages
» Import GML coverage schema components
» User-defined coverage types Schemas defining coverages
» Range parameters shall be substitutable for AbstractValue
» Coverage document Schemas defining coverages
» Introduction Import GML observation schema components
» User-defined observation types Schemas defining observations
» Observation collections Schemas defining observations
» Observations are features Schemas defining observations
» Observation collection document Schemas defining observations
» Introduction Import GML dictionary schema components
» User-defined definition types Schemas defining dictionaries and definitions
» User-defined dictionary types Schemas defining dictionaries and definitions
» Introduction Schemas defining values
» Import GML value objects schema components
» Construction of new value types
» GML profiles of the GML schema
» Overview Change Requests | OGC
» remoteSchema member Base schema components
» ArrayAssociationType Base schema components
» members Base schema components
» featureProperty, featureMember, featureMembers Base schema components
» StringOrRefType Base schema components
» Array, ArrayType, Bag, BagType
» Basic types, Null Change Requests | OGC
» location, LocationPropertyType, LocationKeyWord, LocationString
» coordinates Coordinate geometry, geometric primitives
» pos in EnvelopeType Coordinate geometry, geometric primitives
» pointRep Coordinate geometry, geometric primitives
» polygonPatches Coordinate geometry, geometric primitives
» trianglePatches Coordinate geometry, geometric primitives
» baseGeographicCRS GeographicCRS Coordinate reference systems
» GeocentricCRS uom Coordinate reference systems
» ObliqueCartesianCS Coordinate reference systems
» TemporalCS Coordinate reference systems
» greenwichLongitude Coordinate reference systems
» AbstractOperation Coordinate reference systems
» dmsAngleValue Coordinate reference systems
» Renamed property elements Coordinate reference systems
» SuccessionType MovingObjectStatus Temporal information and dynamic features
» track Temporal information and dynamic features
» DefinitionCollection Definitions and dictionaries
» definitionMember Definitions and dictionaries
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