GML

GML is an XML (Extensible Mark-up Language) grammar for expressing geographic features. GML serves as a modelling language for geographic systems as well as an open interchange format for geographic transactions on the Internet.

• More information can be found on the Open Geospatial Consortium (OGC): http://www.opengeospatial.org/standards/gml.

• The XML specifications that GML is based on are available from the World Wide Web Consortium (W3C): http://www.w3.org.

• Information about Unicode and UTF-8, the character encoding we have chosen, is available on the Unicode Consortium website: http://www.unicode.org.

XML schema

XML schemas are used to validate the format and content of the GML. The GML 3.2.1 specification provides a set of schemas that define the GML feature constructs and geometric types. These are designed to be used as a basis for building application-specific schemas, which define the data content.

The Ordnance Survey application schemas that are referenced by the data are available from our website at: http://www.ordnancesurvey.co.uk/xml/schema.

These schemas make use of XML Schema Definitions (XSDs) and Document Type Definitions (DTDs) produced by the W3C that are available from the W3C website at: http://www.w3.org/XML/1998/namespace.html.

Namespaces

xlink – http://www.w3.org/1999/xlink

gml – http://www.opengis.net/gml

osgb – http://www.ordnancesurvey.co.uk/xml/namespaces/osgb

xml – http://www.w3.org/XML/1998/namespace