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# Well-Known Text Representation of Spatial Reference Systems
[Coordinate System]

This extended BNF grammar represents the syntax of a Well-Known Text (WKT) specification of a Spatial Reference System (SRS), also known as a coordinate system. The grammar is taken verbatim from [OGC01-009] and is reproduced here for convenience.

    <math transform> = <param mt> | <concat mt> | <inv mt> | <passthrough mt>
    <param mt> = PARAM_MT["<classification name>" {,<parameter>}* ]
    <parameter> = PARAMETER["<name>", <value>]
    <value> = <number>
    <concat mt> = CONCAT_MT[<math transform> {,<math transform>}* ]
    <inv mt> = INVERSE_MT[<math transform>]
    <passthrough mt> = PASSTHROUGH_MT[<integer>, <math transform>]
    <coordinate system> = <horz cs> | <geocentric cs> | <vert cs> | <compd cs> | <fitted cs> | <local cs>
    <horz cs> = <geographic cs> | <projected cs>
    <projected cs> = PROJCS["<name>", <geographic cs>, <projection>, {<parameter>,}* <linear unit> {,<twin axes>}{,<authority>}]
    <projection> = PROJECTION["<name>" {,<authority>}]
    <geographic cs> = GEOGCS["<name>", <datum>, <prime meridian>, <angular unit> {,<twin axes>} {,<authority>}]
    <datum> = DATUM["<name>", <spheroid> {,<to wgs84>} {,<authority>}]
    <spheroid> = SPHEROID["<name>", <semi-major axis>, <inverse flattening> {,<authority>}]
    <semi-major axis> = <number>
    <inverse flattening> = <number>
    <prime meridian> = PRIMEM["<name>", <longitude> {,<authority>}]
    <longitude> = <number>
    <angular unit> = <unit>
    <linear unit> = <unit>
    <unit> = UNIT["<name>", <conversion factor> {,<authority>}]
    <conversion factor> = <number>
    <geocentric cs> = GEOCCS["<name>", <datum>, <prime meridian>, <linear unit> {,<axis>, <axis>, <axis>} {,<authority>}]
    <authority> = AUTHORITY["<name>", "<code>"]
    <vert cs> = VERT_CS["<name>", <vert datum>, <linear unit>, {<axis>,} {,<authority>}]
    <vert datum> = VERT_DATUM["<name>", <datum type> {,<authority>}]
    <datum type> = <number>
    <compd cs> = COMPD_CS["<name>", <head cs>, <tail cs> {,<authority>}]
    <head cs> = <coordinate system>
    <tail cs> = <coordinate system>
    <twin axes> = <axis>, <axis>
    <axis> = AXIS["<name>", NORTH | SOUTH | EAST | WEST | UP | DOWN | OTHER]
    <to wgs84s> = TOWGS84[<seven param>]
    <seven param> = <dx>, <dy>, <dz>, <ex>, <ey>, <ez>, <ppm>
    <dx> = <number>
    <dy> = <number>
    <dz> = <number>
    <ex> = <number>
    <ey> = <number>
    <ez> = <number>
    <ppm> = <number>
    <fitted cs> = FITTED_CS["<name>", <to base>, <base cs>]
    <to base> = <math transform>
    <base cs> = <coordinate system>
    <local cs> = LOCAL_CS["<name>", <local datum>, <unit>, <axis>, {,<axis>}* {,<authority>}]
    <local datum> = LOCAL_DATUM["<name>", <datum type> {,<authority>}]

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