end to being able to write data in a format that can be read by old versions. [Computer and Information Sciences] 
n., A duplicate copy of all or portions of software or data files on a system made for safety purposes. [Computer and Information
n., The minimum conditions necessary to enable the preserver to attest to the authenticity of copies of a creator's digital records in the custody of the preserver. [Archives] 
bit 
n., A duplicate of a document saved in the file format in which it was originally cre