Convert from twip to X unit

Unit Definition (twip)
A twip (which stands for Twentieth of a Point) is a typographical measurement. It is also used as the default measurement in Visual Basic. A twip is 1/1440 of an inch when derived from the PostScript point at 72 to the inch, as opposed to the printer's point at 72.27 to the inch.

Unit Definition (X unit)
The X-unit (symbol xu) is a unit of length formerly used to measure the wavelength of X-rays and gamma rays. The X-unit is approximately 1.0021×10-13 metre. Defined by the Swedish physicist Karl Manne Georg Siegbahn (1886-1978) in 1925, the X-unit could not at that time be measured directly; the definition was instead made in terms of the spacing between planes of the calcite crystals used in the measuring apparatus.