When you are about to open a drawing, Tekla Structures displays a notification on the status of the drawing. The options are:
Someone is already editing it.
Someone has already edited it (drawing has been saved to their computer, but not yet to the server).
The drawing has already been saved and there is a newer version available on the server.
Note: Locks for drawings are only used when a drawing is edited manually, not for example when drawings are automatically edited through cloning.
Note that to lock edited drawings, the XS_COLLECT_MODEL_HISTORY advanced option must be set to TRUE.