This is root element of this document which contains name space definitions for the document elements. It's a referenced element. For detailed description, please refer referenced element doc. It's a referenced element. For detailed description, please refer referenced element doc. Description is not available. This field holds a unique number (identifier) of the differential group. Provide an extension hook to customize DiffGrpRef. Provide an extension hook to localize DiffGrpRef. This type can hold a string of max length of 10 characters.