Absolute URIs on the Network

  • http://docbook.org/rng/4.2/docbook.rng

  • http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd

  • urn:publicid:-:OASIS:DTD+DocBook+XML+V4.2:EN

  • http://docbook.sourceforge.net/release/xsl/current/html/docbook.xsl

These offer the most unambiguous identification.