Text Encoding Initiative

The TEI Consortium has released The XML Version of the TEI Guidelines This is from the introduction:

The primary goal of this revision has been to make available a new and corrected version of the TEI Guidelines which:

is expressed in XML and conforms to a TEI-conformant XML DTD;
generates a set of DTD fragments that can be combined together to form either SGML or XML document type definitions;
corrects blatant errors, typographical mishaps, and other egregious editorial oversights;
can be processed and maintained using readily available XML tools instead of the special-purpose ad hoc software originally used for TEI P3.

A second major design goal of this revision has been to ensure that the DTD fragments generated would not break existing documents: in other words, that any document conforming to the original TEI P3 SGML DTD would also conform to the new XML version of it. Although full backwards compatibility cannot be guaranteed, we believe our implementation is consistent with that goal.