As of the next release of the TEI Guidelines, all references to
datatypes named "data.XYZ" must be replaced with "teidata.XYZ".
This is part of the conversion to "Pure ODD", that is, ODDs that do
not rely directly on RELAX NG. The use of "data.XYZ" was deprecated
in version 3.1.0 released 2016-12 -- as of that release the
Guidelines themselves recommend (and use) "teidata.XYZ" not
"data.XYZ", and the "tagdoc" summary information page for each
"data.XYZ" datatype has a warning in a red box.
The next release of P5 is scheduled for January, 2019. (Then why does
the subject say "2 week warning"? Because in roughly 2 weeks the
"data.XYZ" will be removed from the development branch of P5 in our
GitHub repository -- those few who use TEI directly from there will
be affected immediately; the vast majority of TEI users will not be
affected until January 2019.)