Specifies the search path for the tfontsub.cf, which specifies substitute font styles or family names when processing fonts.

Make a copy of tfontsub.cf before you make any modifications.

If you want to make a custom tfontsub.cf file automatically available, use the Arbortext-path\custom\lib directory to load it automatically upon startup (avoiding the need to set an environment variable). If you create a custom tfontsub.cf file for a particular locale, you can put it the appropriate subdirectory of Arbortext-path\custom\lib\locale.