Item Number Constraint Group
Defines an item constraint group.
For example if we had two constraints:
BLOCKS->128..TNT->..64
Imagine a situation where the player has 125 TNT:
If the TNT was processed first it would be thrown out since the TNT limit says that we have too much TNT.
If the BLOCKS constraint was processed first, the TNT would be kept since the BLOCKS constraint is not yet satisfied.