Generic Parameters

Used to specify the 63 character descriptive name of the coordinate system being defined.

Used to specify the datum key name to which a geodetically referenced coordinate system is to be referenced to. The ellipsoid used is a part of this datum definition. Presence of a valid datum key name here indicates that the coordinate system is geodetically referenced. Either a DT_NAME specification, or an EL_NAME specification must be provided for each coordinate system definition. If both DT_NAME and EL_NAME specifications are provided, the EL_NAME specification is ignored.

When features tagged with this type of coordinate system are reprojected, no datum transformation will be applied.

Used to specify the ellipsoid key name for a cartographically referenced coordinate system. A coordinate system is cartographically referenced to the ellipsoid named by this specification if, and only if, the datum key name specification is omitted. If both DT_NAME and EL_NAME specifications are provided, the EL_NAME specification is ignored.

Used to specify the origin latitude of the coordinate system. This value is specified in degrees relative to the equator. Use positive numbers for north latitude, negative numbers for south latitude.

Used to specify the origin longitude of the coordinate system. This value is specified in degrees and is always relative to the Greenwich prime meridian. Use positive numbers for east longitude, negative numbers for west longitude.

Used to specify the scale reduction which may apply to a coordinate system. This value is ignored by the many projections which do not support this feature. The value may be specified as a decimal number, e.g. 0.9996, or as a ratio, e.g. 1:2500. A value of 1.0 or greater is unusual, but is accepted.

Used to specify the minimum X value which is to be considered non-zero. X coordinate values whose absolute value is less than the value specified here will be converted to hard zeros. This is used to suppress coordinate output such as 4.3472E-07 which can be of value in certain applications. A value of 0.0 is assumed if no specification is made.

Used to specify the minimum Y value which is to be considered non-zero. Y coordinate values whose absolute value is less than the value specified here will be converted to hard zeros. This is used to suppress coordinate output such as 4.3472E-07 which can be of value in certain applications. A value of 0.0 is assumed if no specification is made.

Used to specify the value of as many as 24 parameters which are specific to the particular projection in use. The use of these items varies from one projection to another. The value is always a real number. Where a longitude is specified, it must be given in degrees, relative to Greenwich, where west longitude and south latitude are negative. Where a latitude is expected, it must be given in degrees relative to the equator where north latitude is positive and south latitude is negative. When an azimuth is specified, it must be given in degrees east of north (i.e. west of north would be negative).

Used to specify the value of the false easting of the coordinate system. A value of 0.0 is assumed if no specification is made.

Used to specify the value of the false northing of the coordinate system. A value of 0.0 is assumed if no specification is made.

Used to specify the code name of the projection upon which the coordinate system is based.

Used to specify the name of the system unit for the coordinate system being defined.

Used to classify coordinate systems into groups to make selection of a coordinate system from the 1,000+ provided a bit easier.

Used to specify the source of the information used to define this coordinate system, 63 characters maximum.

Used to indicate the quadrant of the cartesian coordinates produced by the coordinate system. Zero or 1 indicate the normal right handed cartesian system where X increases to the east, and Y increases to the north. Quadrants are numbered counterclockwise, therefore a value of 2 specifies a cartesian system where X increases to the west, while Y increases north. A value of 3 indicates that X increases to the west and Y increases to the south. A value of 4 indicates that X increases to the east and Y increases to the south. A negative value will cause the axes to be swapped after the appropriate quadrant is applied. A value of 1 is assumed if this specification is absent.

This parameter is optional and can be used to specify the minimum longitude of the useful range of the coordinate system. The value is given in degrees relative to Greenwich. Positive values indicate east longitude, while negative values indicate west longitude. Its value should be normalized between -360 and +360 and when used must be algebraically less than the MAX_LNG parameter.

This parameter is optional and can be used to specify the maximum longitude of the useful range of the coordinate system. The value is given in degrees relative to Greenwich. Positive values indicate east longitude, while negative values indicate west longitude. Its value should be normalized between -360 and +360 and when used must be algebraically greater than the MIN_LNG parameter.

This parameter is optional and can be used to specify the minimum latitude of the useful range of the coordinate system. The value is given in degrees relative to the equator. Positive values indicate north latitude while negative values indicate south latitude. Its value should be normalized between -90 and +90 and when used must be algebraically less than the MAX_LAT parameter.

This parameter is optional and can be used to specify the maximum latitude of the useful range of the coordinate system. The value is given in degrees relative to the equator. Positive values indicate north latitude while negative values indicate south latitude. Its value should be normalized between -90 and +90 and when used must be algebraically greater than the MIN_LAT parameter.

This parameter is optional and can be used to specify the minimum X coordinate value of the useful range of the coordinate system. The value is given in system units. Its value must be algebraically less than the MAX_XX parameter.

This parameter is optional and can be used to specify the maximum X coordinate value of the useful range of the coordinate system. The value is given in system units. Its value must be algebraically greater than the MIN_XX parameter.

This parameter is optional and can be used to specify the minimum Y coordinate value of the useful range of the coordinate system. The value is given in system units. Its value must be algebraically less than the MAX_YY parameter.