function tt_open()
When Tool&Task is started, 3 tables are opened by tt_open() and kept open during the complete session.
<gUserDataTT>hfiles\defines.dbf in select(1)
<gUserDataTT>hfiles\tt_prot.dbf in select(2)
<gUserDataTT>hfiles\printers.dbf in select(3)
If you want to close these files in your program, use the command tt_close() and, when your procedure has finished tt_open() again.