1 Twip is exactly one twentieth (1/20) of a PostScript point. A PostScript point itself being 1/72 of an inch, making a twip 1/1440 inch. 1 Twip is approximately 1.763889 x 10-5 meters (SI base unit). 1 twp ≈ 0.000017638888888889 m.
1 Chain (Gunter's Surveyor's):
A survey Chain from Edmund Gunter's system having 100 metal links and being 66 feet, or 4 rods, in length. Used in land surveying. One chain (Gunter's Surveyor's)is 4 rods, 22 yards, or 66 feet. 1 ch (Gunter's Surveyor's) = 20.1168 m (SI base unit).