Interop “mandatory” optional parameters

Question

Application was built using MS interop, to export .xls to infoPath and vice versa. It was developed in VS 2010, but now transferred to VS 2008. Project fails to build, as the marvellous interop lib, requires a bunch of crappy parameters to be set (although they are marked as optional in msdn). If putting "null" values, app crashes. There are no code samples on msdn, resolving this issue. So what do I put there?

Answer 1

Pass Type.Missing .

If it's a ref parameter, you'll need to declare a variable to pass by reference.