Files in the SGML/XML parser:

catalog.c		Handle SGML_CATALOG_FILES
catalog.h		
charmap.c		Character classification and mapping
dtd.h			Include file for DTD primitives
dtd2pl.c		Main file for dtd2pl: convert DTD to Prolog
error.c			Utilities for generating Prolog exceptions
error.h
model.c			State engine for handling DDT content model
model.h
parser.c		The parser itself
parser.h
prolog.c		Print DTD in Prolog source (used by dtd2pl)
prolog.h
sgml.c			Main file for sgml (stand-alone parser)
sgml2pl.c		SWI-Prolog foreign code wrapper
sgmldefs.h		General definitions
util.c			Basic character handling and utilities
util.h
