In System Modeler a session is always a multi user session. In order to protect the integrity of the Model database there are a number of choices for ensuring that elements of the Model, or the whole model itself, can be reserved (locked) for exclusive use. Reservation prevents more than one user having access to, and changing the content of the Model at the same time.
Logic Editor is initially opened in view mode. View mode does not request a write lock for the method from the model. A lock is then requested when the logic is modified, preventing other users from obtaining write access to the same method. When the method is locked, the Reserved By property indicates the user holding the lock. Other users are able to obtain read-only access to the method in its form prior to the change. The method is unlocked when the logic is saved, or Logic Editor is closed.
In all types of element reservation, if a reservation fails because the element is reserved by another user, you are notified. When a reservation is successful, the "Reserved By" property in the Property window for the reserved element displays the name of the user who has reserved it.
This level of protection occurs irrespective of whether the additional security of Source Control is available in the project. When Source Control is available it is implied that the Model database is read-only. This means that elements cannot be modified until they are checked out. System Modeler automatically checks out elements from Source Control prior to making it available for editing.
Note: All the functions of element reservation and source control rely on the user having been granted security access to the Model and the element(s) in the Model.
Refer to the following for more information on element reservation: