>Any ideas how to determine is a database in use is opened shared or exclusively?

Cannot remind some direct way, but you could use DBSETPROP() trying to make some dummy change (e.g. change comment to some field). If DBC opened exclusively you will succeed, and set lExclusive=.t., if not you should be stopped by some error code. Trapping this error, you resolve the problem (lExclusive=.f.).