PropertyHandle :: CanUpdate - Can selected instance be modified

The function checks, whether an instance has been selected in the property handle and whether the selected instance can be updated or not.The function returns true, when updating the instance is possible and false otherwise.

There are several reasons for not being up-datable:

1. The property handle is opened for read, only
2. The instance is persistent write protected
3. The instance is locked by another property handle (read in write mode)
4. The current application does not have rights for updating the instance (disabled by context)
5. The instance is an embedded part of another instance which cannot be updated
6. The property handle is invalid.
7. Updating is denied by context handler (client or server) TypeContext::canUpdate()