If you need to be a little more concise, give this a try:
Code:
Function IsAlpha3(pchr As Variant) As Boolean
IsAlpha3 = Switch(Asc(pchr) >= 65 And Asc(pchr) <= 90, True, Asc(pchr) >= 97 And Asc(pchr) <= 122, True, True, False)
End Function
you can call it from the debug (immediate) window with:
I said sorry because it was not the most accurate solution, although I bet it works for your needs, but would fail if say, $ or space was in third position as it would say it was a letter ie non numeric.