perlsgml 1:19970918-12.2.0ubuntu1 (amd64 binary) in ubuntu breezy

tools to build and analyze SGML or XML document type definitions.
 dtd2html generates a suite of linked HTML documents listing the components and
 features of each element in an SGML Document Type Definition (DTD).
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 dtddiff shows differences between two DTDs.
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 dtdtree shows the hierarchy tree (in ASCII) of SGML elements in a DTD.
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 dtdview is an interactive program for studying an SGML DTD.
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 stripsgml strips SGML markup from a file, and also attempts to translate
 entity references to standard ASCII characters.