About reserved and unreserved checkouts

A reserved checkout guarantees that no merge will be needed when you check in your changes.

An element can have one or more branches. Each branch can have at most one reserved checkout and any number of unreserved checkouts. Performing a reserved checkout guarantees you the right to create the successor to the version that you checked out. If several users perform unreserved checkouts, one (and only one) of those users can create the successor version. When you check in a version that was checked out unreserved, the predecessor version of your checkout may no longer be the latest version on the branch from which you checked out your version. In this case, you must merge changes from the latest version on the branch to your checked-out version before you can check it in.