Gear Display for Reverse

[gtihk]

I have a ADL and would like to display R when reverse is selected. Could anyone help please?
I set up a conversion table and put -1 for reverse, but it does not seem to work.

[David Ferguson]

The ADL LCD is an 7-segment LED, so it can't display an R, but can display digits 0-9, We often choose 7 or 9 for reverse.