Using unit definitions Units schema

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16.2.4 UnitDefinition, UnitDefinitionType

A gml:UnitDefinition is a general definition of a unit of measure. This generic element is used only for units for which no relationship with other units or units systems is known. It is declared in the schema as follows: element name=UnitDefinition type=gml:UnitDefinitionType substitutionGroup=gml:Definition complexType name=UnitDefinitionType complexContent extension base=gml:DefinitionType sequence element ref=gml:quantityType minOccurs=0 element ref=gml:quantityTypeReference minOccurs=0 element ref=gml:catalogSymbol minOccurs=0 sequence extension complexContent complexType The content model of gml:UnitDefinition adds three additional properties to gml:Definition described in 15.2.1, gml:quantityType, gml:quantityTypeReference and gml:catalogSymbol. The gml:catalogSymbol property optionally gives the short symbol used for this unit. This element is usually used when the relationship of this unit to other units or units systems is unknown.

16.2.5 quantityType, quantityTypeReference

The gml:quantityType and gml:quantityTypeReference properties indicate the phenomenon to which the units apply. They are declared as follows: element name=quantityType type=gml:StringOrRefType element name=quantityTypeReference type=gml:ReferenceType This element contains an informal description of the phenomenon or type of physical quantity that is measured or observed. EXAMPLE length, angle, time, pressure, or temperature. When the physical quantity is the result of an observation or measurement, this term is known as observable type or measurand. The use of gml:quantityType for references to remote values is deprecated. gml:quantityTypeReference shall be used instead.

16.2.6 catalogSymbol

The catalogSymbol is the preferred lexical symbol used for this unit of measure. It is declared as follows: element name=catalogSymbol type=gml:CodeType The codeSpace attribute in gml:CodeType identifies a namespace for the catalog symbol value, and might reference the external catalog. The string value in gml:CodeType contains the value of a symbol that should be unique within this catalog namespace. This symbol often appears explicitly in the catalog, but it could be a combination of symbols using a specified algebra of units.