reference — Describes an external document
reference : xmlns:xlink, xlink:type, refID, author, title, [classification], [accession], date, [xlink:href] description?
xmlns:xlink
The value of this attribute must be "http://www.w3.org/1999/xlink". If omitted, it should be provided by the parser since it is specified in the DTD.
xlink:type
The value of this attribute must be "simple". If omitted, it should be provided by the parser since it is specified in the DTD.
refID
author
title
classification
accession
(optional) The accession number (ISBN or organization report number) of the document.
date
xlink:href
(optional) A URL to an on-line copy of the referenced document.
2011-03-31