the "Standing" correct me if im wrong but you get it by reading the map tile of where you are opening the corpse or container, and thats just the stack.. it doesnt really matter anymore i think.. in other versions, depending on what value you typed you could open containers that were hidden under other items without removing the items that are on top of it, but it seems to be fixed now..

now the "Backpacks" one is which Slot you wanna open your backpack/container..
they work as above..
starts from 0..
._______________________
|Backpack __________|-|□|X|
|--------|--------|--------|--------|
|--------|--------|--------|--------| <--------- 0
|¯¯¯¯¯|¯¯¯¯¯|¯¯¯¯¯|¯¯¯¯¯|
|_____|_____|_____|_____|
|Bag ______________|-|□|X|
|--------|--------|--------|--------|
|--------|--------|--------|--------| <--------- 1
|¯¯¯¯¯|¯¯¯¯¯|¯¯¯¯¯|¯¯¯¯¯|
|_____|_____|_____|_____|
|
Dead Demon_______ |-|□|X|
|--------|--------|--------|--------|
|--------|--------|--------|--------| <--------- 2
|¯¯¯¯¯|¯¯¯¯¯|¯¯¯¯¯|¯¯¯¯¯|
|_____|_____|_____|_____|