A supplemental language-specific lexicon is optional, and spell checking will function correctly if it is not present or empty.
The supplemental lexicon are to be deployed on a GN4 workstation in the same directory where the GN4 applications are, usually \TERA\BIN. It gets automatically created as an empty file (on the first spell check of any user on that computer). See Deploying main and supplemental lexicons.
Its name is ssceXX.tlx. It is an ASCII file, and systems administrators can manually add words in it, by means of any suitable text editor. For rules, see Words.
Note
You can use the supplemental lexicon for the specific language also to add banned words.
See also
Supplemental lexicon for all languages