A.L.I.C.E. stands for "all-purpose, lightweight, individual, carrying equipment." There's a gigantic amount of room in the pack--enough for a five day outing. Inside the pack is basically one large 'stuff sack' with a smaller pouch near the top. The top pouch is easy to get to, and it holds all the stuff you'll want easy access to plus some.
Outside of the main compartment are a number of smaller pouches for 'on the fly' access. Three big pouches are about the size you need for a couple MRE's.
There are mounting points all over the pack, so adding alice compatible stuff is easy.