PrimeMeridian, greenwichLongitude Geodetic datum .1 GeodeticDatum

Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 121 A gml:PrimeMeridian defines the origin from which longitude values are determined. The default value for the prime meridian gml:identifier value is Greenwich. element name=greenwichLongitude type=gml:AngleType gml:greenwichLongitude is the longitude of the prime meridian measured from the Greenwich meridian, positive eastward. If t he value of the prime meridian ―name‖ is Greenwich then the value of greenwichLongitude shall be 0 degrees. The property uses gml:AngleType.

12.5.3.8 PrimeMeridianPropertyType

complexType name=PrimeMeridianPropertyType sequence minOccurs=0 element ref=gml:PrimeMeridian sequence attributeGroup ref=gml:AssociationAttributeGroup complexType gml:PrimeMeridianPropertyType is a property type for association roles to a prime meridian, either referencing or containing the definition of that meridian. 12.5.4 Other concrete datums 12.5.4.1 EngineeringDatum element name=EngineeringDatum type=gml:EngineeringDatumType substitutionGroup=gml:AbstractDatum complexType name=EngineeringDatumType complexContent extension base=gml:AbstractDatumType complexContent complexType gml:EngineeringDatum defines the origin of an engineering coordinate reference system, and is used in a region around that origin. This origin may be fixed with respect to the Earth such as a defined point at a construction site, or be a defined point on a moving vehicle such as on a ship or satellite.

12.5.4.2 EngineeringDatumPropertyType

complexType name=EngineeringDatumPropertyType sequence minOccurs=0 element ref=gml:EngineeringDatum sequence attributeGroup ref=gml:AssociationAttributeGroup complexType gml:EngineeringDatumPropertyType is a property type for association roles to an engineering datum, either referencing or containing the definition of that datum.

12.5.4.3 ImageDatum

element name=ImageDatum type=gml:ImageDatumType substitutionGroup=gml:AbstractDatum complexType name=ImageDatumType complexContent extension base=gml:AbstractDatumType 122 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. sequence element ref=gml:pixelInCell sequence extension complexContent complexType gml:ImageDatum defines the origin of an image coordinate reference system, and is used in a local context only. For an image datum, the anchor definition is usually either the centre of the image or the corner of the image. For more information, see ISO 19111:2007, B.3.5.

12.5.4.4 pixelInCell

element name=pixelInCell type=gml:CodeWithAuthorityType gml:pixelInCell is a specification of the way an image grid is associated with the image data attributes. The required codeSpace attribute shall reference a source of information specifying the values and meanings of all the allowed string values for this property.

12.5.4.5 ImageDatumPropertyType

complexType name=ImageDatumPropertyType sequence minOccurs=0 element ref=gml:ImageDatum sequence attributeGroup ref=gml:AssociationAttributeGroup complexType gml:ImageDatumPropertyType is a property type for association roles to an image datum, either referencing or containing the definition of that datum.

12.5.4.6 VerticalDatum

element name=VerticalDatum type=gml:VerticalDatumType substitutionGroup=gml:AbstractDatum complexType name=VerticalDatumType complexContent extension base=gml:AbstractDatumType complexContent complexType gml:VerticalDatum is a textual description andor a set of parameters identifying a particular reference level surface used as a zero-height surface, including its position with respect to the Earth for any of the height types recognized by this International Standard.

12.5.4.7 VerticalDatumPropertyType

complexType name=VerticalDatumPropertyType sequence minOccurs=0 element ref=gml:VerticalDatum sequence attributeGroup ref=gml:AssociationAttributeGroup complexType gml:VerticalDatumPropertyType is property type for association roles to a vertical datum, either referencing or containing the definition of that datum.