> Because there's no way to KNOW if a procedure is select-able. Is it?

There is way - existence of outputs.

> As far as I can tell, a procedure without "suspend" never returns values.
> So using "select" when there are output parameters is not sufficient.

This is IB\FB feature. Other servers has its own features.

> Using EXEC that would return a resultset (if available) would be very
> easy to use... IMO of course.

What if resultset is not availaible ?

Roman propose always return resultset, even if SP has no SUSPEND.
But this can break existing applications. Therefore there are another
proposition -
use new special syntax for such call's. Ok... what else from JDBC\ADO\OLEDB\etc
don't fit in FB's SQL dialect ? Will we make new syntax for every new client
access
layer ?

If JDBC will follow simple rule about how to call our SP's and documented
it i see no problem, sorry.

Regards,
Vlad