Whoops, I realize I was not clear. There is no standard way to find
out if an object has been deleted.
Also there is no "exists()" function. The TWG decided that an explicit
"exists()" function would allow an application to determine if an XSet
does exist even if the application has to rights to read it. Instead
it was adopted that an error (exception in Java) indicates that a
specific XSet is not accessible. This means that that the application
is unable to open the XSet because it is either not in the system, or
the application does not have rights to read the XSet.
Applications can tell if XSets exist within their authorization sphere
by attempting to open. When the inaccessible error is returned, it
means that the XSet to which the application does have rights to read,
does not exist.