separation sheet
n.
a form filed in the original location of an item, indicating that the item is stored elsewhere
Notes
A separation sheet preserves the context of items that are stored in a different location by creating a record at the original location. For example, a folded map may be removed from a folder so that it may be stored flat or a nitrate negative may put in cold storage to protect surrounding documents and to retard deterioration. A separation sheet describing the item and indicating its current location is put in the original's place to let people know of its existence.