point
Lengthexact by definition
The point is exactly 1/72 of an inch, 0.3527 mm. It is the unit of type size and of every vertical measurement in page layout: leading, rule weight and the space above a paragraph are all set in points, and 12 points make a pica.
Watch out: The 1/72.27 in point is still called the "TeX point" and appears in typesetting literature. The difference is about 0.4%, invisible on a single character and a couple of millimetres over a full page depth.
| 1 pt | 0.00035277778 m |
Desktop publishing settled this. Traditional printer's points ran near 1/72.27 in in the Anglo-American system and differed again in the Didot system used on the continent. PostScript in the 1980s defined the point as exactly 1/72 in so that the arithmetic worked in whole numbers, and that value won.