Encountered enough of these to make it worth while adding a page on them. Also the manual is 400 pages long, which is a bit excessive to work through for simple, common task of adding STX, so here is a cheat sheet:

Adding STX/ETX

Step 1 - set Barcode Structure as Prefix + Data + Suffix

 

Step 2 - set Prefix

 

Restoring Data + ENTER

Step 1 - set Barcode Structure as  Data + Suffix

 

Step 2 - set Suffix