In some cases, two organizations will both try to find a pilot for the same mission leg. This is known as sharing a leg. Whichever organization finds a pilot first informs the other organization and it becomes their leg. The other organization becomes the linking organization and enters the mission leg as a linking.
While the leg is being worked on, that is, prior to a pilot being assigned, this field is used to indicate to the coordinator that another organization is working on the leg as well. This is a drop-down or combo box populated by the records in the linking organizations table. Null is also an option for this field when the leg is not being shared.