Theological Markup Language, a new markup language that is being used to mark up texts for the Christian Classics Ethereal Library and other projects. This XML application can be thought of as HTML with additions for electronic books and rich digital libraries, with special support for theological needs such as scripture references and Strongs numberings. When books have been prepared in ThML, many new features become possible in the CCEL: subject and scripture reference indexes for books and for the whole library, intelligent searching, automatic conversion to other formats, "lining up" documents in various ways such as parallel columns, and more.
http://www.ccel.org/ThML/