A container for all extensions present in the document. A container for all extensions present in the document. A single extension for private use. A single extension for private use. A single extension for private use. An identifier for the Extension assigned by the creator of the extension. A name for the Extension assigned by the creator of the extension. An agency that maintains one or more Extensions. The name of the agency that maintains the Extension. The version of the Extension. A URI for the Agency that maintains the Extension. A URI for the Extension. A code for reason the Extension is being included. A description of the reason for the Extension. The definition of the extension content.