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1. Computer memory, usually magnetic disks,storing data and programs. Sections of this information canthen be copied into the main memory (RAM) for processing.Backing store is cheaper but RAM is faster. Such a hierarchyof memory devices allows a trade-off between performance andcost.2. Character storage in memory or on disk, as opposedto displayed or printed characters. This distinction isimportant where the visual ordering of characters differs fromthe order in which they are stored, e.g. bidirectional ornon-spacing layout.In a Unicode encoding, text is stored in sequential order inthe backing store. Logical or backing store order correspondsto the order in which text is typed on the keyboard (aftercorrections such as insertions, deletions, and overtyping). Atext rendering process converts Unicode text in the backingstore to readable text.["The Unicode Standard: Worldwide Character Encoding", Version1.0, Vol. 1. Addison-Wesley, 1991].