Hello Nadya,

I don't know if my answer is your solution, but I'll try.

Do this test:

Put a TextBox on a Form and set it:
ThisForm.TextBox1.Format = "M"
ThisForm.TextBox1.InputMask = "Yes,No"

Run the form and then, press SPACE BAR (Or press Y and N) when the focus will on the TextBox1.

I use it a lot, since FoxPro DOS 2.6. I don't know why the help (VFP 5 and 7) show this option like "Included by backward compatible"

When I said If I don't know if it will help you was because I use this solution with Character field.

Please, replay me if it works...

Bye!