backing store

1.	(storage)	backing store - Computer memory, usually magnetic disks, storing data and programs. Sections of this information can then be copied into the main memory (RAM) for processing. Backing store is cheaper but RAM is faster. Such a hierarchy of memory devices allows a trade-off between performance and cost.
2.	(text)	backing store - Character storage in memory or on disk, as opposed to displayed or printed characters. This distinction is important where the visual ordering of characters differs from the order in which they are stored, e.g. bidirectional or non-spacing layout. In a Unicode encoding, text is stored in sequential order in the backing store. Logical or backing store order corresponds to the order in which text is typed on the keyboard (after corrections such as insertions, deletions, and overtyping). A text rendering process converts Unicode text in the backing store to readable text. ["The Unicode Standard: Worldwide Character Encoding", Version
3.		backing store - 0, Vol. 1. Addison-Wesley, 1991].