sgml2html (and other sgml2*) complains like this /usr/bin/nsgmls:/usr/share/xml/docbook/dtd/4.1.2/ent/iso-amsr.ent:23:17:E \"X2256\" is not a function name unless delete line CATALOG \"/etc/sgml/xml-docbook-4.1.2.cat\" from /etc/sgml/catalog file --- --- I suggest remove this line completely because of /etc/xml/catalog file exists for it