The Open GIS Consortium, supporting Geospatial and Information Technolgy Industries with open standards specifications, has now released Geography Markup Language (GML) 2.0 with a complete W3C XML Schema notation. The Geography Markup Language (GML) "is an XML encoding for the transport and storage of geographic information, including both the spatial and non-spatial properties of geographic features." The 2.0 specification "defines the XML Schema syntax, mechanisms, and conventions that provide an open, vendor-neutral framework for the definition of geospatial application schemas and objects, allow profiles that support proper subsets of GML framework descriptive capabilities, etc. Sections 1 and 2 of the new specification present the background information and modeling concepts that are needed to understand GML. Section 3 presents the GML conceptual model which is independent of encoding. Section 4 presents material which discusses the encoding of the GML conceptual model using the XML Schema definition language (XSDL). This material is intended to demonstrate how to employ the normative GML geometry and feature schemas specified in Appendices A and B of this document. Section 5 of this document presents the rules for the development of conformant GML application schemas. Section 6 presents examples to illustrate techniques for constructing compliant GML application to model recurring geographic themes."
[February 28, 2001] Geography Markup Language (GML) 2.0. Edited by Simon Cox (CSIRO Exploration & Mining), Adrian Cuthbert (SpotOn MOBILE), Ron Lake (Galdos Systems, Inc.), and Richard Martell (Galdos Systems, Inc.). OGC Document Number: 01-029. February 20, 2001. Also in PDF and in .ZIP format. Abstract: "The Geography Markup Language (GML) is an XML encoding for the transport and storage of geographic information, including both the spatial and non-spatial properties of geographic features. This specification defines the XML Schema syntax, mechanisms, and conventions that (1) Provide an open, vendor-neutral framework for the definition of geospatial application schemas and objects; (2) Allow profiles that support proper subsets of GML framework descriptive capabilities; (3) Support the description of geospatial application schemas for specialized domains and information communities; (4) Enable the creation and maintenance of linked geographic application schemas and datasets; (5) Support the storage and transport of application schemas and data sets; (6) Increase the ability of organizations to share geographic application schemas and the information they describe. Implementers may decide to store geographic application schemas and information in GML, or they may decide to convert from some other storage format on demand and use GML only for schema and data transport."
Components in the OGC Geocoding specification are available via an Open GIS Schema repository.