Public Function IsSheetNameValid(SheetName As String) As Boolean
    IsSheetNameValid = False          ' Set Default
    If Len(SheetName) = 0 Then Exit Function
    If Len(SheetName) > 31 Then Exit Function
    Dim InvalidCharacters As Variant
    InvalidCharacters = Array("/", "\", "[", "]", "*", "?", ":")
    Dim x As Integer
    For x = LBound(InvalidCharacters) To UBound(InvalidCharacters)
        If InStr(SheetName, (InvalidCharacters(i))) > 0 Then Exit Function
    Next
    IsSheetNameValid = True
End Function