There is only one file type that uses the .TAG extension:
DataFlex Data File
A TAG file is a data file used by DataFlex and SQL Connectivity Kit. It contains a line delimited list of the names of fields defined in the table of a .DAT DataFlex data file.
The TAG file is one of several data files used by DataFlex, along with the .FD, K, and VLD files. Every DAT DataFlex data file has a TAG and FD file. These files bear the same name as the DAT data file.
DataFlex is a tool used to develop Windows desktop, mobile, and web business applications on one framework-based platform. It is used in a variety of industries, including government, transportation, health care, retail, agriculture, legal, financial services, broadcasting, manufacturing, churches, and public utilities.
Updated: March 7, 2017