The little letter to the right of the neutral or 0 position tells you that moving the stick in that direction changes the mode to that mode.
The display is two parts. The left part is the Gear Number Indicator. The right part is a s shift diagram (like you find on shift knobs). But since what happens when you move the shift lever to the right changes, the letter on the shift diagram also changes.
In the early cars, S is sequential manual mode (only shifts when you tell it via the paddles), A is auto mode (shifts when it thinks it should).
A Big A next to the gear number tells you it is in Auto Mode. No letter next to the gear number means you are in S mode.
'95 Alpine M3 LTW
'00 Dakar M Roadster
'02 Topaz M3
Red/White SRF #4 (Chassis 561)