The problem is that your terminal emulator is sending the same
character (tab) for the Tab key and for Shift-Tab. Use the emulator
program Keyboard Mapping feature to change the mapping for Shift-Tab
to Backtab. If your emulator program does not have a "Backtab" option,
just pick an unused character (control character or foreign letter)
as the map for Shift-Tab.
Next, in uni-SPF use the 0.K.2 "update' feature to map Shift-Tab
to the BACKTAB uni-SPF key. This will add the key mapping to the
user's local profile in the table file ISPKBND.tbl in your $HOME
directory. Optionally, you may make this mapping permanent for all
users using the 0.K.3.2 keybind export panel, which places the key
mapping in an installation directory.
You may use this same procedure correct any other problems you
see, or just to customize the operation of uni-SPF. For example,
many users like to have a key for Newline, which is not on the standard