sgml2xml-isoent converts an SGML document to XML,
with support for the ISO entities.
This is done by using
sgml2xml(1) from the
SP package (or
osx(1) from the OpenSP package),
and the declaration for the XML version of the ISO entities
is added to the output.
This means that the output of this conversion
should work as-is with any XML tool.
This program is often used for processing SGML DocBook documents
with XML-based tools. In particular, db2x_xsltproc(1)
calls this program as part of its --sgml
option. On the other hand, it is probably not helpful for
migrating a source SGML text file to XML, since the conversion
mangles the original formatting.
Since the XML version of the ISO entities
are referred to directly, not via a DTD, this tool
also works with document types other than DocBook.