Function IsCharacter(ByVal Expression As String) As Boolean
IsCharacter = False
Dim i As Integer
Dim c As Long
On Error GoTo ErrTrap
If Expression = "" Then Exit Function
IsCharacter = True
For i = 1 To Len(Expression)
c = Asc(Mid(Expression, i, 1))
If Not ((c >= 65 And c <= 90) Or (c >= 97 And c <= 122)) Then
IsCharacter = False
Exit For
End If
Next
Exit Function