Many development shops desire to limit checkouts on a branch to a single checkout rather than allow the developer to perform an "unreserved" checkout. These shops would prefer that the second engineer communicate with the first engineer to gain write access to the element or that the second engineer work on a separate branch. This bit assures this and prevents the need to merge on the same branch, which is frowned upon since it's more difficult to determine which feature the merge is for.
If a second checkout for an element is attempted for a branch then a dialog similar to the one below is displayed:
| Value | Defines this feature as... |
|---|---|
| 0 | disabled |
| 1 | enabled |