There is a simple way to test if a character in a string is a letter.
Just by using the UCase() And LCase() functions.
Public Function IsLetter(Char As String)
Dim sTemp As String
sTemp = Left$(Char, 1)
IsLetter = (StrComp(UCase(sTemp), LCase(sTemp),
vbBinaryCompare) <> 0)
Note: I use the StrComp function, to make it work independent of Option Compare.