Whether this McDBNode is still an operational and accessible instance.

A Boolean value.  

object.IsValid

The IsValid Property syntax has these parts:

McDBNode instances are always associated with backing data in their McDBDatabase files. However, to be valid, this backing data must be available. Due to security changes, aborted transactions, deletion, and other operations, it is possible for the backing data of an McDBNode to become unavailable. Since it is impossible to "take back" the COM object handles that may reference it, the Database Engine merely invalidates the handles that are no longer valid. Invalidated McDBNode instances will throw OLE_E_BLANK for all of their properties and methods. This property returns whether this McDBNode IsValid (i.e. NOT in such a state).