The .dat files is located in 'C:\Program Files\Datatex\tng\data'.
The are basically 2 types:
1dataxxxx and 2dataxxxx .dat
tng*.dat
The tng*.dat files are the configuration and setup files.
The latest version is the current data files in use, for example:
1data_1.0.5.1.dat
2data_1.0.5.1.dat.
Where 1.0.5.1 is the current TNG version number. Never remove these 2 files.
The older 1dataxxxx and 2dataxxxx .dat files is a remainder of the
previous versions of TNG and may be removed.