You normally give this order to a community. Every unit built henceforth at that community will be issued the link order. Once issued, a community movement order will remain, turn after turn, until changed or canceled. To cancel this order, order the community to link to "NOONE".
When a unit receives a link order, it will travel to the community which is the
destination of the link. If the community is not reached in one turn, the unit
continues moving on subsequent turns, until it reaches its final destination.
The unit moves via the quickest path (lowest MP cost). If the destination
community has a movement order of its own, the unit will receive the movement
order when it arrives, otherwise the unit will stop at the destination
community. This order is canceled if the unit retreats from battle, dies in
combat, or is given new movement orders.