Source : Free On-Line Dictionary of Computing

twip
     
         (TWentIeth of a Point) 1/20 of a {Postscript
        point}, or 1/1440th of an inch.  There are thus 1440 twips to
        an inch or about 567 twips to a centimeter.
     
        Twips are used in {Microsoft} formats and products, notably
        {Rich Text Format}, {Visual BASIC}, {Visual C++}, and {printer
        drivers}; and in {IBM} {AFP} products.
     
        Twips were devised in the olden days to describe the sizes of
        characters produced by {dot matrix printers} that were
        constrained to multiples of either 12 or 10 dots per inch.
     
        [Is it definitely relative to a _Postscript_ point, as opposed
        to one of the other definitions of {point}?]
     
        (2002-03-11)