40d:Refuse

Refuse is a stockpile meant to designate where garbage can be placed. A typical refuse pile will hold items like bones, shells, non-pet/friendly corpses, remains, chunks, and any worn out items such as clothing.

Corpses, chunks, body parts, skin, and food all can rot, emitting miasma when stored on Inside Dark Subterranean tiles. It is important to know where you want to place your refuse stockpile beforehand, as miasma causes an unhappy thought. Designating a refuse stockpile on any tile with Light Above Ground will prevent miasma and makes the items subject to seasonal cleanups (this includes bones, skulls, and shells). If you want a stockpile inside your fortress, you can contain miasma with walls and doors. Alternatively, you can dig an open pit down to the z-level most convenient for you. Light need only touch the tile once for it to become permanently Light Above Ground, after which you can rebuild the roof.

It is a good idea to use two layers of doors (i.e. a short corridor with two doors, one after the other). This is to prevent miasma from leaking out into the fortress if a dwarf uses the door at the wrong time. You can contain miasma completely by building a diagonal entrance to the refuse area, since miasma cannot travel diagonally. This is considered an exploit however, and is likely to be fixed/changed at some point.