The ECM platform allows check in and check out features.
A working copy in the Checked Out state can be modified freely by users having access rights to the document. A document ceases to be Checked Out when the Check In is active.
A working copy in the Checked In state is identical to the version that was created when the Check In was activated on the working copy. In the Checked In state, a working copy is (at low level) not modifiable. To be modified it must be switched to the Checked Out state first. This latter operation is automatically done in the platform when a document is modified.
Check in and check out features can be activated from the user interface or called from a web service.