OpenJade, the follow-up to Jade by James Clark, is an implementation of
the ISO/IEC 10179:1996 standard DSSSL (Document Style, Semantics, and
Specification Language); pronounce it "dissl"--it rhymes with whistle.

It has back-ends for SGML, RTF, MIF, TeX, and HTML.

The parser, "nsgmls," and helper tools like "sgmlnorm," "spam,"
"spent," and "sx" are now included in the separate "opensp" package.