http://www.eqemulator.net/forums/showthread.php?t=24208
This never got added in, but roamboxes use a similar method for specifying a section of zone. Perhaps you can take a look at Ailia's code in there and see if you can adapt it to the zone part of the database, instead of roamboxes?
PS: off topic, but can we have advnpcspawn added? I'm tired of people using #npcspawn and not knowing how the schema works. It's more good as a learning tool than anything. It also adds roamboxes, which are a good replacement for grids.