Source : Free On-Line Dictionary of Computing

flat ASCII
     
         (Or "plain ASCII") Said of a text file that contains
        only 7-bit {ASCII} characters and uses only ASCII-standard
        {control characters} (that is, has no embedded codes specific
        to a particular text formatter {markup} language, or output
        device, and no {meta}-characters).
     
        Compare {flat file}.
     
        [{Jargon File}]
     
        (1996-01-26)