Xlinks — Object associations and remote properties
8.2 Basic types
8.2.1 Overview
W3C XML Schema provides a set of built- in ―simple‖ types which define methods for representing values as literals without internal markup. These are described in W3C XML Schema Part 2:2001. Because GML is an XML encoding in which instances are described using XML Schema, these simple types shall be used as far as possible and practical for the representation of data types. W3C XML Schema also provides methods for defining new simple types by restriction and combination of the built-in types, and complex types, with simple content, but which also have XML attributes. In many places where a suitable built-in simple type is not available, simple content types derived using the XML Schema mechanisms are used for the representation of data types in GML. A set of these simple content types that are required by several GML components are defined in the basicTypes schema, as well as some elements based on them. These are primarily based around components needed to record amounts, counts, flags and terms, together with support for exceptions or null values. NOTE The basic types and elements are described in the basicTypes schema document in Annex C. The schema is identified by the following location-independent name using URN syntax: urn:x-ogc:specification:gml:schema-xsd:basicTypes:3.2.18.2.2 Relationship with ISOTS 19103
ISOTS 19103 defines basic types for the conceptual schemas in the ISO 19100 series of International Standards. GML implements a subset of these basic types as described in D.2.2. NOTE Some of the ISOTS 19103 basic types are specified in other schema documents of the GML schema: units of measure are specified in Clause 16 and vector in 10.1.4.5. 8.2.3 Simple types 8.2.3.1 NilReasonType gml:NilReasonType defines a content model that allows recording of an explanation for a void value or other exception. simpleType name=NilReasonEnumeration union simpleType restriction base=string enumeration value=inapplicable enumeration value=missing enumeration value=template enumeration value=unknown enumeration value=withheld Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 37 restriction simpleType simpleType restriction base=string pattern value=other:\w{2,} restriction simpleType union simpleType simpleType name=NilReasonType union memberTypes=gml:NilReasonEnumeration anyURI simpleType gml:NilReasonType is a union of the following enumerated values: inapplicable: there is no value missing: the correct value is not readily available to the sender of this data. Furthermore, a correct value may not exist template: the value will be available later unknown: the correct value is not known to, and not computable by, the sender of this data. However, a correct value probably exists withheld: the value is not divulged other:+text: other brief explanation, where text is a string of two or more characters with no included spaces and anyURI which should refer to a resource which describes the reason for the exception A particular community may choose to assign more detailed semantics to the standard values provided. Alternatively, the URI method enables a specific or more complete explanation for the absence of a value to be provided elsewhere and indicated by-reference in an instance document. gml:NilReasonType is used as a member of a union in a number of simple content types defined below see 8.2.3.4, 8.2.4.1, 8.2.4.2, 8.2.4.3 where it is necessary to permit a value from the NilReasonType union as an alternative to the primary type.8.2.3.2 Elements declared to be “nillable”
The XML Schema attribute nillable may be included in any element declaration within a schema. NOTE By default the schema attribute nillable has a value of ―false‖. EXAMPLE 1 The following element declarations illustrate the use of the nillable attribute: element name=‖amount‖ type=‖double‖ nillable=‖true‖ element ref=‖my:amount‖ nillable=‖true‖Parts
» 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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