The bodybag.2da file is the .2da file that defines what sorts of container placeables can be left behind when a creature or placeable fades out upon death and has items to drop as loot. (This implicitly excludes creatures that have been flagged as leaving a lootable corpse, as they do not fade out while they still have items to drop.) Body bags are basically a convenience mechanism, as it is easier for a player to obtain multiple items from a container than to pick each item up off the ground.