Your UDF will look something like:
Code:
Public Function Foo(strSource As String, strDestination As String) As String
Select Case strSource
Case "us"
Select Case strDestination
Case "us"
Foo = "0"
Case "mx"
Foo = "48"
Case "ca"
Foo = "24"
Case Else
Foo = "missing Destination country designation"
End Select
Case "mx"
Select Case strDestination
Case "us"
Foo = "0"
Case "mx"
Foo = "48"
Case "ca"
Foo = "72"
Case Else
Foo = "missing Destination country designation"
End Select
Case "ca"
Select Case strDestination
Case "us"
Foo = "0"
Case "mx"
Foo = "24"
Case "ca"
Foo = "72"
Case Else
Foo = "missing Destination country designation"
End Select
Case Else
Foo = "missing Source country designation"
End Select
End Function