It do the following in the Command Window:

OPEN DATABASE mainDBC EXCLUSIVE

and no error is reported.
- This even thoughI can see mainDBC in the databases dropdown in the VFP toolbar.

The I do:

VALIDATE DATABASE

in the command window.
The resultant output states:
"Need EXCLUSIVE writeable access to rebuild structural index."

Why doesn't the EXCLUSIVE clause on the OPEN DATABASE command give an error?

cheers