Before changing the contents of a file or editing item properties, you should exclusively lock the file or item. This action informs other team members that you intend to make changes. Files, change requests, requirements, tasks, and topics can all be locked.
Exclusively locking an item prevents others from creating new revisions of it before the lock has been released. You can lock and unlock any type of item as a separate operation. In addition, you can lock and unlock files as part of the check-in and check-out processes.
If an item is exclusively locked by someone else, you can review its properties but cannot change them. Normally the words Read Only and the name of the user who has locked the item will appear on the title bar.