XT is an implementation in Java of XSLT. This version of XT implements the PR-xslt-19991008 version of XSLT. Stylesheets written for earlier versions of the XSLT WD must be converted before they can be used with this version of XT.

4xt has stepped into the role of supporting this ancient product. Although there doesn't seem to be any new development as far as bringing it up to date with the new specs there are a lot of new addons.