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 constraints.xsd schema implements the UML conceptual schema defined in A.2.3 of ISO 19115:2003. It contains the implementation of the following classes: MD_Constraints, MD_LegalConstraints, MD_SecurityConstraints, MD_ClassificationCode, MD_RestrictionCode. Restrictions on the access and use of a dataset or metadata Restrictions and legal prerequisites for accessing and using the dataset. Handling restrictions imposed on the dataset because of national security, privacy, or other concerns