To ensure integrity of the model and to prevent two persons from modifying the same element at the same time, an element is automatically reserved (locked) by System Modeler to that user, when it is about to be modified. System Modeler determines that an element is about to be modified if the element is opened in its editor and a key press is made, or the mouse moved, when any part of the content of the editor is selected.
Automatic reservation occurs regardless of whether Source Control is available or not. If Source Control is available the element is also be checked out to this user if it has not already checked out by another user, or separately by the same user.
The point at which a reservation is removed depends on the type of edit being done, as follows:
When the changes are saved.
When the editor is closed for a Documentation or Logic editor, whether or not you have selected the save option.
In the case of renaming or changing an attribute, when the change has been made persistent by saving it in the model.
With automatic reservation, the granularity for reservation is at the element level. For example, in the case of Logic, the method is locked, and in the case of any modification made in the editor, the editor element gets locked.
Also, refer to Manual Reservation.