About reserved checkouts
The Reserve command changes an unreserved checkout to a reserved checkout.
A reserved checkout gives you the exclusive right to check in the element when you are finished. With an unreserved checkout, you may need to merge your changes at checkin if someone else checked in the same element before you did.
This choice is available only when the item you select is checked out as unreserved.
The Unreserve command changes a reserved checkout to an unreserved checkout. This choice is available only when the item you select is checked out as unreserved.