Metric typographic units

Typography is an old art. Long before the introduction of the international standard system of units (“metric system”), printing equipment manufacturers all over the world have established a bewildering variety units to measure length, many of which continue to be used today:

1 point (Didot) = 0.376 mm = 1/72 of a French royal inch (27.07 mm)
1 point (TeX)* = 0.3514598035 mm = 1/72.27 inch
1 point (Postscript) = 0.3527777778 mm = 1/72 inch
1 point (l’Imprimerie nationale, IN) = 0.4 mm
1 pica (TeX) = 4.217517642 mm = 12 points (TeX)*
1 pica (Postscript) = 4.233333333 mm = 12 points (Postscript)
1 cicero = 4.531 mm = 12 points (Didot)

*TeX = is a typesetting system created by Donald Knuth. Together with the METAFONT language for font description and the Computer Modern typeface, it was designed with two main goals in mind: first, to allow anybody to produce high-quality books using a reasonable amount of effort, and, second, to provide a system that would give the exact same results on all computers, now and in the future. It is free and is popular in academia, especially in the mathematics, physics, computer science, political science, and engineering communities. It has largely displaced Unix troff, the other favored formatter, in many Unix installations, which use both for different purposes.
TeX is considered by some to be the best way to typeset complex mathematical formulae but especially in the form of LaTeX and other template packages, is now also being used for many other typesetting tasks. For more information go to wikipedia.org/wiki/TeX

The printing and publishing software market is at present dominated by manufacturers (Apple, Adobe, Microsoft, Quark, etc.) located in the United States, the last country on the planet that has yet to make significant progress towards the introduction of modern standard units. As a result, the use of standard units is far from well established in digital typography, to the significant annoyance of users all over the world. W3C’s CSS2 specification

Font Sizes

DIN 16507-2
This draft standard defines (among many others) the following two font measures:
Font size.
This is the baseline distance for which the font was designed. A font should normally be identified and selected by this size, because the intended baseline distance is much more relevant for practical layout work than the actual dimensions of certain characters.
Font height.
This is the height in mm of letters such as k or H. Typically, the font height is around 72% of the font size, but this is of course at the discretion of the font designer.

DIN 16507-2 contains a list of preferred metric font sizes, together with the corresponding preferred 72% font heights in mm. The table below shows in addition to these values from the standard also the corresponding preferred 72% font heights in Postscript points for easier comparison with the old font sizes. Note: the point sizes of US fonts do not always refer to the k/H height that is defined by DIN as the font height. Some font manufacturers (e.g., Knuth) also refer to the size of taller characters such as “(”, so be careful not to convert incompatible measurements and try to find out the baseline distance for which a font was originally designed of you want to convert properly to metric sizes.

(The above mm values are from the old DIN 16507-2:1984-05 draft. If you implement metric font sizes, please make sure you get the latest version of the actual standard from DIN.) for more detailed information on type and fonts go to www.cl.cam.ac.uk more on font problems