EPSG:27700

Projected coordinate system

OSGB 1936 / British National Grid -- United Kingdom Ordnance Survey

Covered area

Center coordinates
308165.30 607733.40

Projected bounds:
-84667.14 11795.97
608366.68 1230247.30

WGS84 bounds:
-8.74 49.81
1.84 60.9

Selected transformation

United Kingdom (UK)

code 5339

Accuracy 1.0 m
grid file

Method: NTv2

Remarks: Parameter values taken from OSGB 1936 to ETRS89 (1) (tfm code 5338) assuming that ETRS89 is coincident with WGS 84 within the accuracy of the tfm. Within accuracy of the tfm equivalent to OSGB 1936 / British National Grid to WGS 84 (2) (tfm code 15956).

Information source: OGP

Revision date: 2011-02-03

Attributes

Unit: metre

Geodetic CRS: OSGB 1936

Datum: OSGB 1936

Ellipsoid: Airy 1830

Prime meridian: Greenwich

Data source: OGP

Information source: Ordnance Survey of Great Britain.

Revision date: 2005-05-27

NadGrid file: OSTN02_NTv2.gsb

Definition: Well Known Text (WKT)

PROJCS["OSGB 1936 / British National Grid",
    GEOGCS["OSGB 1936",
        DATUM["OSGB_1936",
            SPHEROID["Airy 1830",6377563.396,299.3249646,
                AUTHORITY["EPSG","7001"]],
            TOWGS84[446.448,-125.157,542.06,0.15,0.247,0.842,-20.489],
            AUTHORITY["EPSG","6277"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","4277"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",49],
    PARAMETER["central_meridian",-2],
    PARAMETER["scale_factor",0.9996012717],
    PARAMETER["false_easting",400000],
    PARAMETER["false_northing",-100000],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AXIS["Easting",EAST],
    AXIS["Northing",NORTH],
    AUTHORITY["EPSG","27700"]]
PROJCS["OSGB 1936 / British National Grid",
    GEOGCS["OSGB 1936",
        DATUM["OSGB_1936",
            SPHEROID["Airy 1830",6377563.396,299.3249646,
                AUTHORITY["EPSG","7001"]],
            TOWGS84[446.448,-125.157,542.06,0.15,0.247,0.842,-20.489],
            AUTHORITY["EPSG","6277"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","4277"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",49],
    PARAMETER["central_meridian",-2],
    PARAMETER["scale_factor",0.9996012717],
    PARAMETER["false_easting",400000],
    PARAMETER["false_northing",-100000],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AXIS["Easting",EAST],
    AXIS["Northing",NORTH],
    AUTHORITY["EPSG","27700"]]

Definition: ESRI WKT

PROJCS["OSGB_1936_British_National_Grid",GEOGCS["GCS_OSGB 1936",DATUM["D_OSGB_1936",SPHEROID["Airy_1830",6377563.396,299.3249646]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",49],PARAMETER["central_meridian",-2],PARAMETER["scale_factor",0.9996012717],PARAMETER["false_easting",400000],PARAMETER["false_northing",-100000],UNIT["Meter",1]]

Definition: PROJ.4

+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m +no_defs 

Definition: JavaScript (Proj4js)

proj4.defs("EPSG:27700","+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m +no_defs");

Definition: OGC GML

<?xml version="1.0" encoding="UTF-8"?>
 <gml:ProjectedCRS xmlns:epsg="urn:x-ogp:spec:schema-xsd:EPSG:1.0:dataset" xmlns:gml="http://www.opengis.net/gml/3.2" xmlns:xlink="http://www.w3.org/1999/xlink" gml:id="epsg-crs-27700">
   <gml:metaDataProperty>
      <epsg:CommonMetaData>
         <epsg:type>projected</epsg:type>
         <epsg:alias alias="British National Grid" code="1002" codeSpace="urn:ogc:def:naming-system:EPSG::7302" />
         <epsg:alias alias="(GB_OSGB36 / NATIONALGRID - see alias remarks)" code="2916" codeSpace="urn:ogc:def:naming-system:EPSG::7307">
            <epsg:remarks>This EuroGeographics identifier is for a CRS similar to this but with CS axes in order north, east.</epsg:remarks>
         </epsg:alias>
         <epsg:informationSource>Ordnance Survey of Great Britain.</epsg:informationSource>
         <epsg:revisionDate>2005-05-27</epsg:revisionDate>
         <epsg:changes>
            <epsg:changeID xlink:href="urn:ogc:def:change-request:EPSG::2003.010" />
            <epsg:changeID xlink:href="urn:ogc:def:change-request:EPSG::2005.180" />
         </epsg:changes>
         <epsg:show>true</epsg:show>
         <epsg:isDeprecated>false</epsg:isDeprecated>
      </epsg:CommonMetaData>
   </gml:metaDataProperty>
   <gml:identifier codeSpace="OGP">urn:ogc:def:crs:EPSG::27700</gml:identifier>
   <gml:name>OSGB 1936 / British National Grid</gml:name>
   <gml:domainOfValidity xlink:href="urn:ogc:def:area:EPSG::1264" />
   <gml:scope>Large and medium scale topographic mapping and engineering survey.</gml:scope>
   <gml:conversion xlink:href="urn:ogc:def:coordinateOperation:EPSG::19916" />
   <gml:baseGeodeticCRS xlink:href="urn:ogc:def:crs:EPSG::4277" />
   <gml:cartesianCS xlink:href="urn:ogc:def:cs:EPSG::4400" />
</gml:ProjectedCRS>
<?xml version="1.0" encoding="UTF-8"?>
 <gml:ProjectedCRS xmlns:epsg="urn:x-ogp:spec:schema-xsd:EPSG:1.0:dataset" xmlns:gml="http://www.opengis.net/gml/3.2" xmlns:xlink="http://www.w3.org/1999/xlink" gml:id="epsg-crs-27700">
   <gml:metaDataProperty>
      <epsg:CommonMetaData>
         <epsg:type>projected</epsg:type>
         <epsg:alias alias="British National Grid" code="1002" codeSpace="urn:ogc:def:naming-system:EPSG::7302" />
         <epsg:alias alias="(GB_OSGB36 / NATIONALGRID - see alias remarks)" code="2916" codeSpace="urn:ogc:def:naming-system:EPSG::7307">
            <epsg:remarks>This EuroGeographics identifier is for a CRS similar to this but with CS axes in order north, east.</epsg:remarks>
         </epsg:alias>
         <epsg:informationSource>Ordnance Survey of Great Britain.</epsg:informationSource>
         <epsg:revisionDate>2005-05-27</epsg:revisionDate>
         <epsg:changes>
            <epsg:changeID xlink:href="urn:ogc:def:change-request:EPSG::2003.010" />
            <epsg:changeID xlink:href="urn:ogc:def:change-request:EPSG::2005.180" />
         </epsg:changes>
         <epsg:show>true</epsg:show>
         <epsg:isDeprecated>false</epsg:isDeprecated>
      </epsg:CommonMetaData>
   </gml:metaDataProperty>
   <gml:identifier codeSpace="OGP">urn:ogc:def:crs:EPSG::27700</gml:identifier>
   <gml:name>OSGB 1936 / British National Grid</gml:name>
   <gml:domainOfValidity xlink:href="urn:ogc:def:area:EPSG::1264" />
   <gml:scope>Large and medium scale topographic mapping and engineering survey.</gml:scope>
   <gml:conversion xlink:href="urn:ogc:def:coordinateOperation:EPSG::19916" />
   <gml:baseGeodeticCRS xlink:href="urn:ogc:def:crs:EPSG::4277" />
   <gml:cartesianCS xlink:href="urn:ogc:def:cs:EPSG::4400" />
</gml:ProjectedCRS>

Definition: XML

<?xml version="1.0" encoding="UTF-8"?>
 <gml:ProjectedCRS gml:id="ogrcrs575327" xmlns:gml="http://www.opengis.net/gml/3.2">
  <gml:srsName>OSGB 1936 / British National Grid</gml:srsName>
  <gml:srsID>
    <gml:name gml:codeSpace="urn:ogc:def:crs:EPSG::">27700</gml:name>
  </gml:srsID>
  <gml:baseCRS>
    <gml:GeographicCRS gml:id="ogrcrs575328">
      <gml:srsName>OSGB 1936</gml:srsName>
      <gml:srsID>
        <gml:name gml:codeSpace="urn:ogc:def:crs:EPSG::">4277</gml:name>
      </gml:srsID>
      <gml:usesEllipsoidalCS>
        <gml:EllipsoidalCS gml:id="ogrcrs575329">
          <gml:csName>ellipsoidal</gml:csName>
          <gml:csID>
            <gml:name gml:codeSpace="urn:ogc:def:cs:EPSG::">6402</gml:name>
          </gml:csID>
          <gml:usesAxis>
            <gml:CoordinateSystemAxis gml:id="ogrcrs575330" gml:uom="urn:ogc:def:uom:EPSG::9102">
              <gml:name>Geodetic latitude</gml:name>
              <gml:axisID>
                <gml:name gml:codeSpace="urn:ogc:def:axis:EPSG::">9901</gml:name>
              </gml:axisID>
              <gml:axisAbbrev>Lat</gml:axisAbbrev>
              <gml:axisDirection>north</gml:axisDirection>
            </gml:CoordinateSystemAxis>
          </gml:usesAxis>
          <gml:usesAxis>
            <gml:CoordinateSystemAxis gml:id="ogrcrs575331" gml:uom="urn:ogc:def:uom:EPSG::9102">
              <gml:name>Geodetic longitude</gml:name>
              <gml:axisID>
                <gml:name gml:codeSpace="urn:ogc:def:axis:EPSG::">9902</gml:name>
              </gml:axisID>
              <gml:axisAbbrev>Lon</gml:axisAbbrev>
              <gml:axisDirection>east</gml:axisDirection>
            </gml:CoordinateSystemAxis>
          </gml:usesAxis>
        </gml:EllipsoidalCS>
      </gml:usesEllipsoidalCS>
      <gml:usesGeodeticDatum>
        <gml:GeodeticDatum gml:id="ogrcrs575332">
          <gml:datumName>OSGB_1936</gml:datumName>
          <gml:datumID>
            <gml:name gml:codeSpace="urn:ogc:def:datum:EPSG::">6277</gml:name>
          </gml:datumID>
          <gml:usesPrimeMeridian>
            <gml:PrimeMeridian gml:id="ogrcrs575333">
              <gml:meridianName>Greenwich</gml:meridianName>
              <gml:meridianID>
                <gml:name gml:codeSpace="urn:ogc:def:meridian:EPSG::">8901</gml:name>
              </gml:meridianID>
              <gml:greenwichLongitude>
                <gml:angle gml:uom="urn:ogc:def:uom:EPSG::9102">0</gml:angle>
              </gml:greenwichLongitude>
            </gml:PrimeMeridian>
          </gml:usesPrimeMeridian>
          <gml:usesEllipsoid>
            <gml:Ellipsoid gml:id="ogrcrs575334">
              <gml:ellipsoidName>Airy 1830</gml:ellipsoidName>
              <gml:ellipsoidID>
                <gml:name gml:codeSpace="urn:ogc:def:ellipsoid:EPSG::">7001</gml:name>
              </gml:ellipsoidID>
              <gml:semiMajorAxis gml:uom="urn:ogc:def:uom:EPSG::9001">6377563.396</gml:semiMajorAxis>
              <gml:secondDefiningParameter>
                <gml:inverseFlattening gml:uom="urn:ogc:def:uom:EPSG::9201">299.3249646</gml:inverseFlattening>
              </gml:secondDefiningParameter>
            </gml:Ellipsoid>
          </gml:usesEllipsoid>
        </gml:GeodeticDatum>
      </gml:usesGeodeticDatum>
    </gml:GeographicCRS>
  </gml:baseCRS>
  <gml:definedByConversion>
    <gml:Conversion gml:id="ogrcrs575335">
      <gml:usesMethod xlink:href="urn:ogc:def:method:EPSG::9807" />
      <gml:usesParameterValue>
        <gml:value gml:uom="urn:ogc:def:uom:EPSG::9102">49</gml:value>
        <gml:valueOfParameter xlink:href="urn:ogc:def:parameter:EPSG::8801" />
      </gml:usesParameterValue>
      <gml:usesParameterValue>
        <gml:value gml:uom="urn:ogc:def:uom:EPSG::9102">-2</gml:value>
        <gml:valueOfParameter xlink:href="urn:ogc:def:parameter:EPSG::8802" />
      </gml:usesParameterValue>
      <gml:usesParameterValue>
        <gml:value gml:uom="urn:ogc:def:uom:EPSG::9001">0.9996012717</gml:value>
        <gml:valueOfParameter xlink:href="urn:ogc:def:parameter:EPSG::8805" />
      </gml:usesParameterValue>
      <gml:usesParameterValue>
        <gml:value gml:uom="urn:ogc:def:uom:EPSG::9001">400000</gml:value>
        <gml:valueOfParameter xlink:href="urn:ogc:def:parameter:EPSG::8806" />
      </gml:usesParameterValue>
      <gml:usesParameterValue>
        <gml:value gml:uom="urn:ogc:def:uom:EPSG::9001">-100000</gml:value>
        <gml:valueOfParameter xlink:href="urn:ogc:def:parameter:EPSG::8807" />
      </gml:usesParameterValue>
    </gml:Conversion>
  </gml:definedByConversion>
  <gml:usesCartesianCS>
    <gml:CartesianCS gml:id="ogrcrs575336">
      <gml:csName>Cartesian</gml:csName>
      <gml:csID>
        <gml:name gml:codeSpace="urn:ogc:def:cs:EPSG::">4400</gml:name>
      </gml:csID>
      <gml:usesAxis>
        <gml:CoordinateSystemAxis gml:id="ogrcrs575337" gml:uom="urn:ogc:def:uom:EPSG::9001">
          <gml:name>Easting</gml:name>
          <gml:axisID>
            <gml:name gml:codeSpace="urn:ogc:def:axis:EPSG::">9906</gml:name>
          </gml:axisID>
          <gml:axisAbbrev>E</gml:axisAbbrev>
          <gml:axisDirection>east</gml:axisDirection>
        </gml:CoordinateSystemAxis>
      </gml:usesAxis>
      <gml:usesAxis>
        <gml:CoordinateSystemAxis gml:id="ogrcrs575338" gml:uom="urn:ogc:def:uom:EPSG::9001">
          <gml:name>Northing</gml:name>
          <gml:axisID>
            <gml:name gml:codeSpace="urn:ogc:def:axis:EPSG::">9907</gml:name>
          </gml:axisID>
          <gml:axisAbbrev>N</gml:axisAbbrev>
          <gml:axisDirection>north</gml:axisDirection>
        </gml:CoordinateSystemAxis>
      </gml:usesAxis>
    </gml:CartesianCS>
  </gml:usesCartesianCS>
</gml:ProjectedCRS>
<?xml version="1.0" encoding="UTF-8"?>
 <gml:ProjectedCRS gml:id="ogrcrs575327" xmlns:gml="http://www.opengis.net/gml/3.2">
  <gml:srsName>OSGB 1936 / British National Grid</gml:srsName>
  <gml:srsID>
    <gml:name gml:codeSpace="urn:ogc:def:crs:EPSG::">27700</gml:name>
  </gml:srsID>
  <gml:baseCRS>
    <gml:GeographicCRS gml:id="ogrcrs575328">
      <gml:srsName>OSGB 1936</gml:srsName>
      <gml:srsID>
        <gml:name gml:codeSpace="urn:ogc:def:crs:EPSG::">4277</gml:name>
      </gml:srsID>
      <gml:usesEllipsoidalCS>
        <gml:EllipsoidalCS gml:id="ogrcrs575329">
          <gml:csName>ellipsoidal</gml:csName>
          <gml:csID>
            <gml:name gml:codeSpace="urn:ogc:def:cs:EPSG::">6402</gml:name>
          </gml:csID>
          <gml:usesAxis>
            <gml:CoordinateSystemAxis gml:id="ogrcrs575330" gml:uom="urn:ogc:def:uom:EPSG::9102">
              <gml:name>Geodetic latitude</gml:name>
              <gml:axisID>
                <gml:name gml:codeSpace="urn:ogc:def:axis:EPSG::">9901</gml:name>
              </gml:axisID>
              <gml:axisAbbrev>Lat</gml:axisAbbrev>
              <gml:axisDirection>north</gml:axisDirection>
            </gml:CoordinateSystemAxis>
          </gml:usesAxis>
          <gml:usesAxis>
            <gml:CoordinateSystemAxis gml:id="ogrcrs575331" gml:uom="urn:ogc:def:uom:EPSG::9102">
              <gml:name>Geodetic longitude</gml:name>
              <gml:axisID>
                <gml:name gml:codeSpace="urn:ogc:def:axis:EPSG::">9902</gml:name>
              </gml:axisID>
              <gml:axisAbbrev>Lon</gml:axisAbbrev>
              <gml:axisDirection>east</gml:axisDirection>
            </gml:CoordinateSystemAxis>
          </gml:usesAxis>
        </gml:EllipsoidalCS>
      </gml:usesEllipsoidalCS>
      <gml:usesGeodeticDatum>
        <gml:GeodeticDatum gml:id="ogrcrs575332">
          <gml:datumName>OSGB_1936</gml:datumName>
          <gml:datumID>
            <gml:name gml:codeSpace="urn:ogc:def:datum:EPSG::">6277</gml:name>
          </gml:datumID>
          <gml:usesPrimeMeridian>
            <gml:PrimeMeridian gml:id="ogrcrs575333">
              <gml:meridianName>Greenwich</gml:meridianName>
              <gml:meridianID>
                <gml:name gml:codeSpace="urn:ogc:def:meridian:EPSG::">8901</gml:name>
              </gml:meridianID>
              <gml:greenwichLongitude>
                <gml:angle gml:uom="urn:ogc:def:uom:EPSG::9102">0</gml:angle>
              </gml:greenwichLongitude>
            </gml:PrimeMeridian>
          </gml:usesPrimeMeridian>
          <gml:usesEllipsoid>
            <gml:Ellipsoid gml:id="ogrcrs575334">
              <gml:ellipsoidName>Airy 1830</gml:ellipsoidName>
              <gml:ellipsoidID>
                <gml:name gml:codeSpace="urn:ogc:def:ellipsoid:EPSG::">7001</gml:name>
              </gml:ellipsoidID>
              <gml:semiMajorAxis gml:uom="urn:ogc:def:uom:EPSG::9001">6377563.396</gml:semiMajorAxis>
              <gml:secondDefiningParameter>
                <gml:inverseFlattening gml:uom="urn:ogc:def:uom:EPSG::9201">299.3249646</gml:inverseFlattening>
              </gml:secondDefiningParameter>
            </gml:Ellipsoid>
          </gml:usesEllipsoid>
        </gml:GeodeticDatum>
      </gml:usesGeodeticDatum>
    </gml:GeographicCRS>
  </gml:baseCRS>
  <gml:definedByConversion>
    <gml:Conversion gml:id="ogrcrs575335">
      <gml:usesMethod xlink:href="urn:ogc:def:method:EPSG::9807" />
      <gml:usesParameterValue>
        <gml:value gml:uom="urn:ogc:def:uom:EPSG::9102">49</gml:value>
        <gml:valueOfParameter xlink:href="urn:ogc:def:parameter:EPSG::8801" />
      </gml:usesParameterValue>
      <gml:usesParameterValue>
        <gml:value gml:uom="urn:ogc:def:uom:EPSG::9102">-2</gml:value>
        <gml:valueOfParameter xlink:href="urn:ogc:def:parameter:EPSG::8802" />
      </gml:usesParameterValue>
      <gml:usesParameterValue>
        <gml:value gml:uom="urn:ogc:def:uom:EPSG::9001">0.9996012717</gml:value>
        <gml:valueOfParameter xlink:href="urn:ogc:def:parameter:EPSG::8805" />
      </gml:usesParameterValue>
      <gml:usesParameterValue>
        <gml:value gml:uom="urn:ogc:def:uom:EPSG::9001">400000</gml:value>
        <gml:valueOfParameter xlink:href="urn:ogc:def:parameter:EPSG::8806" />
      </gml:usesParameterValue>
      <gml:usesParameterValue>
        <gml:value gml:uom="urn:ogc:def:uom:EPSG::9001">-100000</gml:value>
        <gml:valueOfParameter xlink:href="urn:ogc:def:parameter:EPSG::8807" />
      </gml:usesParameterValue>
    </gml:Conversion>
  </gml:definedByConversion>
  <gml:usesCartesianCS>
    <gml:CartesianCS gml:id="ogrcrs575336">
      <gml:csName>Cartesian</gml:csName>
      <gml:csID>
        <gml:name gml:codeSpace="urn:ogc:def:cs:EPSG::">4400</gml:name>
      </gml:csID>
      <gml:usesAxis>
        <gml:CoordinateSystemAxis gml:id="ogrcrs575337" gml:uom="urn:ogc:def:uom:EPSG::9001">
          <gml:name>Easting</gml:name>
          <gml:axisID>
            <gml:name gml:codeSpace="urn:ogc:def:axis:EPSG::">9906</gml:name>
          </gml:axisID>
          <gml:axisAbbrev>E</gml:axisAbbrev>
          <gml:axisDirection>east</gml:axisDirection>
        </gml:CoordinateSystemAxis>
      </gml:usesAxis>
      <gml:usesAxis>
        <gml:CoordinateSystemAxis gml:id="ogrcrs575338" gml:uom="urn:ogc:def:uom:EPSG::9001">
          <gml:name>Northing</gml:name>
          <gml:axisID>
            <gml:name gml:codeSpace="urn:ogc:def:axis:EPSG::">9907</gml:name>
          </gml:axisID>
          <gml:axisAbbrev>N</gml:axisAbbrev>
          <gml:axisDirection>north</gml:axisDirection>
        </gml:CoordinateSystemAxis>
      </gml:usesAxis>
    </gml:CartesianCS>
  </gml:usesCartesianCS>
</gml:ProjectedCRS>

Definition: GeoServer

27700=PROJCS["OSGB 1936 / British National Grid",GEOGCS["OSGB 1936",DATUM["OSGB_1936",SPHEROID["Airy 1830",6377563.396,299.3249646,AUTHORITY["EPSG","7001"]],TOWGS84[446.448,-125.157,542.06,0.15,0.247,0.842,-20.489],AUTHORITY["EPSG","6277"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4277"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",49],PARAMETER["central_meridian",-2],PARAMETER["scale_factor",0.9996012717],PARAMETER["false_easting",400000],PARAMETER["false_northing",-100000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","27700"]]

Definition: MapServer - MAPfile

PROJECTION
	"proj=tmerc"
	"lat_0=49"
	"lon_0=-2"
	"k=0.9996012717"
	"x_0=400000"
	"y_0=-100000"
	"ellps=airy"
	"towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489"
	"units=m"
	"no_defs"
END

Definition: MapServer - Python

wkt = '''PROJCS["OSGB 1936 / British National Grid",GEOGCS["OSGB 1936",DATUM["OSGB_1936",SPHEROID["Airy 1830",6377563.396,299.3249646,AUTHORITY["EPSG","7001"]],TOWGS84[446.448,-125.157,542.06,0.15,0.247,0.842,-20.489],AUTHORITY["EPSG","6277"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4277"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",49],PARAMETER["central_meridian",-2],PARAMETER["scale_factor",0.9996012717],PARAMETER["false_easting",400000],PARAMETER["false_northing",-100000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","27700"]]'''
m = mapObj('')
m.setWKTProjection(ref.ExportToWkt())
lyr = layerObj(m)
lyr.setWKTProjection(ref.ExportToWkt())

Definition: Mapnik

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m +no_defs">
	<Layer srs="+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m +no_defs">
	</Layer>
</Map>

Definition: Mapnik - Python

proj4 = '+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m +no_defs'
m = Map(256,256,proj4)
lyr = Layer('Name',proj4)

Definition: SQL (PostGIS)

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 27700, 'EPSG', 27700, '+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m +no_defs ', 'PROJCS["OSGB 1936 / British National Grid",GEOGCS["OSGB 1936",DATUM["OSGB_1936",SPHEROID["Airy 1830",6377563.396,299.3249646,AUTHORITY["EPSG","7001"]],TOWGS84[446.448,-125.157,542.06,0.15,0.247,0.842,-20.489],AUTHORITY["EPSG","6277"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4277"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",49],PARAMETER["central_meridian",-2],PARAMETER["scale_factor",0.9996012717],PARAMETER["false_easting",400000],PARAMETER["false_northing",-100000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","27700"]]');

Definition: OGC WKT

PROJCS["OSGB 1936 / British National Grid",GEOGCS["OSGB 1936",DATUM["OSGB_1936",SPHEROID["Airy 1830",6377563.396,299.3249646,AUTHORITY["EPSG","7001"]],TOWGS84[446.448,-125.157,542.06,0.15,0.247,0.842,-20.489],AUTHORITY["EPSG","6277"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4277"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",49],PARAMETER["central_meridian",-2],PARAMETER["scale_factor",0.9996012717],PARAMETER["false_easting",400000],PARAMETER["false_northing",-100000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","27700"]]

Definition: USGS

[9, 0, (0.0, 0.0, 0.9996012717, 0.0, -2000000.0, 49000000.0, 400000.0, -100000.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0), 9]