XML mention domain
Use the XML-mention domain elements for mentions of named XML constructs, including
            elements, attributes, entities, processing instructions, and document-type declaration
            components. These elements enable specific typographic effects for different construct
            types,
            precise search and retrieval of specific constructs, and automatic indexing of different
            constructs. This domain is intended to support the description and documentation of
            XML
            document types and XML applications.
         
         
         note
Although the original XML 1.0 Recommendation specifically reserved element
               names beginning with "xml" or "XML"' for the use of the XML standard itself, the subsequent
               introduction of namespaces made the restriction unnecessary. The restriction was formally
               removed in the XML 1.0 Fifth Edition Specification Errata. The OASIS DITA Technical
               Committee acknowledges this revised policy in its use of the semantically precise
               prefix "xml"
               for the XML mention domain.