As part of a macro, I open an input box. Here is the part I'm not sure how
to code: I'd like the input to be restricted to either 1 or 2 alphanumeric
characters ONLY. (no spaces, other symbols, =3 characters, etc.)

1, Ab, 4G, are all OK.
#4, 1 2, A3b are not OK.

Could someone offer a few clues?

Thanks
Bri