The compiled dtd's are currently built by hand. Currently, something like the following will work: ../../src/xemacs -batch -q -l psgml-parse.elc -l psgml-dtd.elc -eval "(progn (sgml-set-global) (setq sgml-no-elements 0) (sgml-compile-dtd \"$(pwd)/html.dtd\" \"$(pwd)/cdtd/html\" []))" Note that the parameters are taken roughly from the ECAT file.
Drazen Kacar <dave@public.srce.hr> writes regarding htmlpro.dtd: You probably want the home page URL, though. Try <URL:http://www.arbornet.org/~silmaril/dtds/html/htmlpro.html> The site cannot be reached sometimes. The mirror exists somewhere, but I don't have the URL.
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.