From Second Life Wiki
Function: integer llGetParcelMaxPrims( vector pos, integer sim_wide );
Returns an integer that is the maximum number of prims allowed on the parcel at pos.
|| position in region coordinates (z component is ignored)
|| TRUE treats all parcels owned by this parcel owner in the sim in a single maximum, FALSE determines the max for the specified parcel
If sim_wide is...
- FALSE then the return is the maximum prims supported by the parcel.
- not FALSE then the return is the number of prims supported by all land in the region owned by the parcel owner.