Stephané: I have an up-to-date potato installation using xemacs (which includes psgml) and all the packages referenced in your HOWTO.
I tried the xml example in the the Writing DocBook section on p.6 in the .ps version. The dtd could not be found until I modified your example to provide the full path. Perhaps the install of some package should modify sgml-data-directory (currently set to "/usr/lib/xemacs-20.4/etc/sgml/") or sgml-system-path (currently set to nil) to point to the right directory. Or you could use the full path in your example. Or both...:) The rest of the example worked fine - thanks for the effort you have put into this. Michael Laing

