Administration > Environment Variables > APTTEXINPUTS — Path Names to Directories Containing Source Files
  
APTTEXINPUTS — Path Names to Directories Containing Source Files
Specifies a search list to directories that contain macro files (.tmx files) and hyphenation rules (.exc and .pat files).
If you want to make .tmx, .exc, and .pat files automatically available, use the Arbortext-path\custom\inputs directory to load them automatically upon startup (avoiding the need to set an environment variable).
Example:
set APTTEXINPUTS=user-path\tmx;%D