DESCRIPTIONsgml2xml-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.