Direction schema direction, DirectionPropertyType

192 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. element name=direction type=gml:DirectionPropertyType complexType name=DirectionPropertyType sequence minOccurs=0 choice element name=DirectionVector type=gml:DirectionVectorType element name=DirectionDescription type=gml:DirectionDescriptionType element name=CompassPoint type=gml:CompassPointEnumeration element name=DirectionKeyword type=gml:CodeType element name=DirectionString type=gml:StringOrRefType choice sequence attributeGroup ref=gml:OwnershipAttributeGroup attributeGroup ref=gml:AssociationAttributeGroup complexType The two alternative kinds of direction specifications, a vector or a description, are specified in the following subclauses.

17.3 DirectionVectorType

Direction vectors are specified by providing components of a vector as follows: complexType name=DirectionVectorType choice element ref=gml:vector sequence element name=horizontalAngle type=gml:AngleType element name=verticalAngle type=gml:AngleType sequence choice complexType The gml:vector element is described in 10.1.4.5. EXAMPLE This form may appear in a data instance as follows: gml:direction gml:DirectionVector gml:vector srsName=wgs840.0 45.0gml:vector gml:DirectionVector gml:direction The use of the alternative representation via angles has been deprecated, gml:vector shall be used instead.

17.4 DirectionDescriptionType

Direction descriptions are specified by a compass point code, a keyword, a textual description or a reference to a description. The gml:DirectionDescriptionType element is declared as follows: complexType name=DirectionDescriptionType choice element name=compassPoint type=gml:CompassPointEnumeration element name=keyword type=gml:CodeType element name=description type=string element name=reference type=gml:ReferenceType choice complexType Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 193 A gml:compassPoint is specified by a simple enumeration string type that is declared as follows: simpleType name=CompassPointEnumeration restriction base=string enumeration value=N enumeration value=NNE enumeration value=NE enumeration value=ENE enumeration value=E enumeration value=ESE enumeration value=SE enumeration value=SSE enumeration value=S enumeration value=SSW enumeration value=SW enumeration value=WSW enumeration value=W enumeration value=WNW enumeration value=NW enumeration value=NNW restriction simpleType These directions are necessarily approximate, giving direction with a precision of 22.5°. It is thus generally unnecessary to specify the reference frame, though this may be detailed in the definition of a GML application language. EXAMPLE 1 This form may appear in a data instance as follows: gml:direction gml:DirectionDescription gml:compassPointWNWgml:compassPoint gml:DirectionDescription gml:direction In addition, the elements to contain text-based descriptions of direction are provided. If the direction is specified using a term from a list, gml:keyword should be used, and the list indicated using the value of the codeSpace attribute. EXAMPLE 2 This form may appear in a data instance as follows: gml:direction gml:DirectionDescription gml:keyword codeSpace=http:my.big.orgtermsdirectiononshoregml:keyword gml:DirectionDescription gml:direction If the direction is described in prose, gml:direction or gml:reference should be used, allowing the value to be included inline or by reference. EXAMPLE 3 This form may appear in a data instance as follows: gml:direction gml:DirectionDescription gml:directionTowards the lighthousegml:direction gml:DirectionDescription gml:direction