Intelligent booking. When booking for instance 200h:s between two dates, the booking should behave intelligently and spread out the 200h:s, but not overbook the resource if he/she is already booked on other work. So the behaviour should be "even out the load, but take current bookings in account and adjust so the resource is not overbooked".

An alternative way of implementing this is to have an option "don't allow overbooking" or "Use intelligent booking" that would make all scheduling of bookings take in account what's already planned on resources and adjust so the resource isn't allowed to be overbooked.