A configuration file stores settings used by software. It has text with key-value pairs and sections. 10% of TRG files save data this way. TRG is a LiveUpdate data format from Symantec. It is used by Norton solutions to store update data. Old versions may not support it.
You can still open TRG files if Norton SystemWorks is installed. Make sure the software is current. New versions support formats old ones don’t.
TRG files are commonly used in China on Windows 10 with Chrome. XMap created LiveUpdate files, which TRG is based on. TriggerReactor scripts use the TRG extension too. They run Minecraft commands when triggered.
Programs can be associated with TRG files in the Windows Registry. Many files are just text. If unknown, try text editors. Knowing the program helps open, edit and print the file.