Geographic MetaData (GMD) extensible markup language is a component of the XML Schema Implementation of Geographic Information Metadata documented in ISO/TS 19139:2007. GMD includes all the definitions of http://www.isotc211.org/2005/gmd namespace. The root document of this namespace is the file gmd.xsd. This maintenance.xsd schema implements the UML conceptual schema defined in A.2.5 of ISO 19115:2003. It contains the implementation of the following classes: MD_MaintenanceInformation, MD_MaintenanceFrequencyCode, MD_ScopeCode, MD_ScopeDescription. Information about the scope and frequency of updating Description of the class of information covered by the information