.GDTB File Extension
What is a GDTB file?
Datafile used by gretl, an open source econometrics program; stores economic data, which includes observations, variables, and descriptions of the included information, in binary format.
NOTE: The data contained in a GDTB file is in binary format, which enables large datasets to be read and written faster. However for smaller datasets around 9 MB or less, the original .GDT plain text format can be used.