Peter,

You are misinformed if you think the major reason for private data sessions is for multi-instance forms. And you may be being presumptious if you think because you don't want two copies of a form open that your users will never want it. Ask the user that has to determine if two custoemr records are in fact the same customer if they would like to see both records at the same time on screen. I think they may answer yes.

Anyway, back to the point, the major reason to use private data sessions is encapsulation. That is having a form object that encapsulates its data and function completely and independent of any other form that may be open at the same time.

Other reasons are number of work areas available, using alias's that make sense instead of unqiue alias' so the work areas can be told apart, testing multi-user code an a single machine, when you get to DLLs and COM servers keeping one server form stomping on the data of another ...

The ability to allow multi-instance forms is simply a nice side effect.