What makes a "flee" command complete?

[PFQNiet]

The "flee" command can be given to units to make them run away from something. But there doesn't appear to be any way to specify how far away they should try to get, or how long they should flee for.

Is it possible to set either of these? Or are these hard-coded (and if so to what values)?

My current alternative is to use "go_to_location" instead, with a target calculated based on the unit's position and the position of the thing the unit is fleeing from, but that seems hacky.