Source : Free On-Line Dictionary of Computing

special-case
     
        To write unique code to handle input to or situations arising
        in a program that are somehow distinguished from normal
        processing.  This would be used for processing of mode
        switches or interrupt characters in an interactive interface
        (as opposed, say, to text entry or normal commands), or for
        processing of {hidden flag}s in the input of a batch program
        or {filter}.
     
        [{Jargon File}]