Bob Stayton has released LiveDTD, a Perl script that parses DTDs into HTML for easy exploration.

Announcing LiveDTD, Stayton writes:

If you have ever worked with a highly parameterized DTD like DocBook or TEI, you know how much the indirection makes you jump around in the DTD to find where something is really defined. It gets worse if you add a customization layer ... You have to track down the "live" one through the marked sections and customization modules. This program does that for you.

Stayton adds that he originally wrote the tool to aid his development of a customization layer for DocBook. An online demo of browsing the XML Spec DTD is available on the LiveDTD site.