Something I don't understand about prim limits

There is something I don't understand about prim limits... when you go to "About Land" -> "Objects", you get the following stats:

Simulator primitive usage
Primitives parcel supports
Primitives on parcel

Now, I've always thought that "Primitives parcel supports" is the absolute number of prims that a parcel can contain. This does not seem to be the case, as I can make my "Primitives on parcel" number go higher than "Primitives parcel supports". I haven't tested how much higher, but I can definitely go higher. So, I don't understand why.

Also, what exactly does the "Simulator primitive usage" number mean? I figured it has something to do with now many "temp" prims can be on the land?

If you own two parcels of land in the same sim (region) you automatically pool your prim limits. The two parcels need not be adjacent.

For instance, if you held 512m of land in the south-west corner of sim "A" and another 512m of land in the north-east corner of sim "A" your total prim allowance in that sim is 234. You could therefore put 234 prims on one parcel if you left the other empty.

And indeed many people do this. You might see now and then a bit of land named 'so-and-so's prim booster' or something like that. They just buy extra land within the same sim, and leave the land empty, because it boosts their prim allowance on their main plot. Note though that land parcels in other sims do not boost your prim allowance, it is strictly within the same sim only.

There is another thing that can be done on private islands, which is 'double prim' land, where you get twice the prims, or something along those lines, but the bottom line is the same -- put double the prims somewhere, you leave somewhere else with no prims.

And, "Simulator prim usage" is the number of prims you have within the whole region / sim. It doesn't have anything to do with temp prims at all in fact.

-Atashi

Ah, so the "Simulator primitive usage" is the number I should really be looking at. All this time I thought I had to stay strictly within the "Primitives parcel supports" value in my sectioned-off chunks of land. Thanks for setting me straight!

Just to clarify this, it's called a "Simulator Object Bonus" (and will show up with that name in the About Land window). Essentially, it tells SL to multiply the number of prims it reports available on any given parcel by some value, which can be anything from 1.1x all the way to 5x or so. Because the number of prims available across the entire island is still the same, this requires the landlord to ensure there are enough spare prims to actually make that number available. "Prim Booster" land is actually often easier to manage because it has better granularity..

Just have a question about this.
If you own 2 512 plots in the same sim and are renting them out to 2 different people, is there a way to stop one resident from using more than their share automatically?
Or would i have to ask them in person to lower their usage (or return the objects myself,)?