"Optionally you can specify which languages your project supports.
Example languages are C, CXX (i.e. C++), Fortran, etc. *By default C and
CXX are enabled if no language options are given.* Specify language
NONE, or use the LANGUAGES keyword and list no languages, to skip
enabling any languages. "
Looks as though c and cxx are the 1%'ers in the "class" system. Might be
good to update this documentation whenever Kitware gets around to it.