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
from /etc/sgml/catalog file
I suggest remove this line completely because of /etc/xml/catalog file exists for it
It\'s a problem of docbook-dtd412-xml,
fixed in docbook-dtd412-xml-1.0-alt3.
The error described does not occur anymore.