: Public abstract <<type>> Class
Created: 10/04/2008 12:16:37
Modified: 14/12/2009 12:09:24
Project:
Advanced:
A datum specifies the relationship of a coordinate system to an object, thus creating a coordinate reference system. For geodetic and vertical coordinate reference systems the datum relates the coordinate system to the earth. With other types of coordinate reference system the datum may relate the coordinate system to another physical or virtual object. A datum uses a parameter or set of parameters that determine the location of the origin of the coordinate reference system. Each datum subtype can be associated with only specific types of coordinate reference systems.<br/><br/>
Attribute
Public CharacterString
  anchorDefinition
Details:
Notes: The datum definition - a description, possibly including coordinates of an identified point or points, of the relationship used to anchor the coordinate system to the Earth or alternate object.<br/><br/>- For a geodetic datum, this anchor may be a point known as the fundamental point, which is traditionally the point where the relationship between geoid and ellipsoid is defined, together with a direction from that point. In other cases, the anchor may consist of a number of points. In those cases, the parameters defining the geoid/ellipsoid relationship have then been averaged for these points, and the coordinates of the points adopted as the datum definition.<br/><br/>- For an engineering datum, the anchor may be an identified physical point with the orientation defined relative to the object.<br/><br/>- For an image datum, the anchor is usually either the centre of the image or the corner of the image. The coordinate system orientation is defined through the CS_AxisDirection class.<br/><br/>
Public Date
  realizationEpoch
Details:
Notes: The time after which this datum definition is valid. This time may be precise (e.g. 1997.0 for IRTF97) or merely a year (e.g. 1986 for NAD83(86)). In the latter case, the epoch usually refers to the year in which a major recalculation of the geodetic control network, underlying the datum, was executed or initiated. An old datum may remain valid after a new datum is defined. Alternatively, a datum may be replaced by a later datum, in which case the realization epoch for the new datum defines the upper limit for the validity of the replaced datum.<br/><br/>
Public EX_Extent
  domainOfValidity
Details:
Notes: Area or region or timeframe in which this datum is valid.<br/><br/>
Public CharacterString
  scope
Details:
Notes: Description of usage, or limitations of usage, for which this datum is valid. If unknown, enter "not known".<br/><br/>
Element Source Role Target Role
«type» SC_SingleCRS
Class   		Name: datum
Derived association to the datum used by this coordinate reference system. 		Name: referenceSystem
Not-navigable derived association from a coordinate reference system that uses this datum.
Details:
Derived association to the datum used by this coordinate reference system.<br/>
Tag Value
byValuePropertyType false
Details:
Values: false
Default: false
Description: Create a property type that requires that the instance is encoded inline (applies to ISO 19136:2007 encoding rule). Always set to false in INSPIRE.
isCollection false
Details:
Values: true | false
Default: false
Description: Identifies the type as an object collection.
noPropertyType false
Details:
Values: false
Default: false
Description: Surpress creation of a standard property type that supports inline or by-reference encoding (applies to ISO 19136:2007 encoding rule). Always set to false in INSPIRE.
persistence persistent
Details:
 
xsdEncodingRule iso19136_2007_INSPIRE_Extensions
Details:
Values: iso19136_2007 | iso19139_2007 | iso19136_2007_INSPIRE_Extensions
Default: iso19136_2007_INSPIRE_Extensions
Description: XML Schema encoding rule to apply
Object Type Connection Direction Notes
«type» TemporalDatum Class Generalization From  
«type» CD_ImageDatum Class Generalization From  
«type» CD_VerticalDatum Class Generalization From  
«type» IO_IdentifiedObject Class Generalization To  
«type» CD_GeodeticDatum Class Generalization From  
«type» CD_EngineeringDatum Class Generalization From  
CT_Datum Class Realization From