Administration > Environment Variables > APTDICTPATH — Specifying Path to User-Defined Dictionaries
  
APTDICTPATH — Specifying Path to User-Defined Dictionaries
Specifies the default search path list for the set userdict option. The search list is the paths to dictionary directories containing user-defined dictionaries for the spelling checker. Specify the directory path containing dictionaries.
The symbolic parameters %H and %Dsymbolic parameters for path list variables may be specified as part of the search path.
If you want to make dictionary files automatically available, use the Arbortext-path\custom\dictionaries directory to load them automatically upon startup (avoiding the need to set an environment variable).