Use a FCL Exception or create my own

I debate this almost daily.  As an example:

Our Middle Tier logic takes a DataSet for an Update. I want to confirm, in

this particular Update method, that the DataTable to update is contained in

the Tables collection. If it's not, I want to throw an exception.

I can throw 'InvalidOperationException' or throw a custom user defined

exception like '<tablename>MissingException'. The sdk states to use FCL

exceptions when possible, however a custom one in this case might be more

meaningful.

What are folks doing in cases like this? That is, cases where a FCL

exception kind of fits but a custom one might be more meaningful.