This would allow you to affect only items below or above an amount.

Example:
all: -1
min: 16
would mean that all items that normally stack less than 16 can be stacked up to 16, but all other items are left where they are.

all: -1
max: 32
would mean that all items that normally stack above 32 can only be stacked to 32, but all other items are left where they are.