---+ The OpenGIS Protocols

   * OpenGIS documents: http://www.opengis.org/specs/?page=specs
   * OpenGIS abstracts: http://www.opengis.org/specs/?page=abstract
   * OpenGIS schemas: http://schemas.opengis.net/
   * download all their schemas: http://ww3.bgbm.org/moin/protocol/documents/schemas.opengis.zip