There is only one file type that uses the .TLG extension:
QuickBooks Transaction Log File
Log file created by QuickBooks, a program used to track personal and company finances; contains a log of all pending uncommitted transactions to a .QBW file; tracks data changes since the last time a proper backup has been created.
In the case of a failure, TLG files can be used used to restore data back to a valid state. Failure conditions include connection failures, program crashes, or QBW file corruption.
TLG files must be kept in the same directory as their corresponding QBW files. They are named with the convention [company name].qbw.tlg.
Updated: January 6, 2010