Example of units dictionary informative

182 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. gml:catalogSymbol codeSpace=http:www.bipm.fren3_SIbase_units.htmlmgml:catalogSymbol gml:unitsSystem xlink:href=http:www.bipm.fren3_SI gml:BaseUnit gml:dictionaryEntry -- … -- gml:Dictionary gml:dictionaryEntry gml:dictionaryEntry gml:Dictionary gml:id=SIDerivedUnits gml:descriptionThe Derived Units from the SI units system. These are all derived as a product of SI Base Units, except degrees Celsius in which the conversion formaula to the SI Base Unit kelvin involves an offset. gml:description gml:identifier codeSpace=http:www.opengeospatial.orginitiatives?iid=79OWS-1.2 SI Derived Unitsgml:identifier gml:dictionaryEntry gml:DerivedUnit gml:id=rad gml:identifier codeSpace=http:www.bipm.fren3_SIradiangml:identifier gml:quantityTypeplane anglegml:quantityType gml:catalogSymbol codeSpace=http:www.bipm.fren3_SIradgml:catalogSymbol gml:derivationUnitTerm uom=m exponent=1 gml:derivationUnitTerm uom=m exponent=-1 gml:DerivedUnit gml:dictionaryEntry -- … -- gml:Dictionary gml:dictionaryEntry gml:dictionaryEntry gml:Dictionary gml:id=ConventionalUnitsDictionary gml:descriptionA collection of Conventional Units. These are units of measure which are either widely used or important within a specific community. For most of these there is 1. a known derivation from more primitive units, which may or may not be SI Base Units, or 2. a known conversion to a preferred unit, which may or may not be an SI Base or Derived unit, through rescaling and offset, or both.gml:description gml:identifier codeSpace=http:www.opengeospatial.orginitiatives?iid=79OWS-1.2 Conventional units.gml:identifier gml:dictionaryEntry gml:DerivedUnit gml:id=m3 gml:identifier codeSpace=http:www.opengeospatial.orginitiatives?iid=79cubic metregml:identifier gml:quantityTypeVolumegml:quantityType gml:derivationUnitTerm uom=m exponent=3 gml:DerivedUnit gml:dictionaryEntry gml:dictionaryEntry gml:ConventionalUnit gml:id=l gml:identifier codeSpace=http:www.opengeospatial.orginitiatives?iid=79litregml:identifier gml:quantityTypeVolumegml:quantityType gml:conversionToPreferredUnit uom=m3 gml:factor0.001gml:factor gml:conversionToPreferredUnit gml:ConventionalUnit gml:dictionaryEntry -- … -- gml:Dictionary gml:dictionaryEntry gml:Dictionary

16.3 Measures schema

16.3.1 Overview

gml:MeasureType is defined in the basicTypes schema. The measure types defined here correspond with a set of convenience measure types described in ISOTS 19103. The XML implementation is based on the XML Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 183 Schema simple type ―double‖ which supports both decimal and scientific notation, and includes an XML attribute ―uom‖ which refers to the units of measure for the value. Note that, there is no requirement to store values using any particular format, and applications receiving elements of this type may choose to coerce the data to any other type as convenient. NOTE The schema document for specific measure types is identified by the following location-independent name using URN syntax: urn:x-ogc:specification:gml:schema-xsd:measures:3.2.1

16.3.2 measure

This is the value of a physical quantity, together with its units. It is declared as follows: element name=measure type=gml:MeasureType See 8.2.3.6 for the definition of gml:MeasureType.

16.3.3 Scalar measure types

A set of specific measure types are defined as vacuous extensions i.e. aliases of gml:MeasureType. A prototypical definition is as follows: complexType name=LengthType simpleContent extension base=gml:MeasureType simpleContent complexType This content model supports the description of a length or distance quantity, with its units. The unit of measure referenced by uom shall be suitable for a length, such as metres or feet. The other measure types that are defined following this pattern are: gml:ScaleType, gml:GridLengthType, gml:AreaType, gml:VolumeType, gml:SpeedType, gml:TimeType, and gml:AngleType . EXAMPLE Elements using these content models might appear in a data instance as follows: my:length uom=m1.76my:length my:scale uom=percent20.my:scale my:gridLength uom=pixelSpacing480my:gridLength my:gridLength uom=imageHeight0.00208333333333my:gridLength my:area uom=ha1.76my:area my:volume uom=l0.45my:volume my:speed uom=kmph73.0my:speed gml:angle uom=gradians95.gml:angle my:time uom=minutes30.my:time NOTE Note that the last element in the example addresses the same functional requirements as the elements in the gml:AbstractTimeLength substitution group, defined in Clause 14.