All CDB Versions are identified by a file called 'Version.xml'; this schema defines the format of this file. CDB is an OGC Standard. Copyright (c) 2016 Open Geospatial Consortium. To obtain additional rights of use, visit http://www.opengeospatial.org/legal/. This element is optional; when present it provides the location of another CDB Version that is linked with the current one. Provides the relative or absolute path to another CDB Version. This choice preserves backward compatibility with version 3.0 of the Specification where a 'comment' element was used to describe the content of a CDB Version. As of CDB 3.1, the prefered syntax for commenting a version is to use the 'Comment' element. Specifies the version of the CDB Standard used to generate the current CDB Version. If 'Specification' is present, the version number indicated here has preceedence over the one specified in 'Version_Specification.xml', if the file exist. If no explicit version is provided either here or in Specification_Version.xml, the version number is deemed to be 3.0. The 'version' attribute is a character string representing the version number of the Specification. The 'authority' attribute is an optional character string identifying the organization that has authority over the standard. When present, the only allowed value is "OGC" and the version number must be '1.0'. When absent, the valid version numbers are 3.0, 3.1, and 3.2. This element is optional; when present, it tells us that the current 'CDB Version' is a 'CDB Extension'. As a result, the whole content of this version is not covered by the Specification. A CDB Extension can contain any datasets, including valid CDB Datasets.