RE: Face header

[Alistair Vining]

> This is wrong.
>
> 1. The standard point, established by international agreement
> well over 100 years ago, as used by Knuth and by type foundries
> everywhere is 1/72.27
> inch or 0.351459mm (number of centimetres to an inch = 2.54, and 2.54 /
> 72.27 = 0.351459). The value below is incorrect.

Nope, Knuth doesn't use the standard point.  From the TeXbook:

'The units have been defined here so that precise conversion to sp [the
internal unit, 1/65536 TeX "pt"] is efficient on a wide variety of
machines.  In order to achieve this, TeX's "pt" has been made slightly
larger than the official printer's point, which was defined to equal
exactly 0.013837 in by the American Typefounders Association in 1886 [cf.
National Bureau of Standards Circular 570 (1956)].  In fact, one classical
point is exactly 0.99999999 pt, so the "error" is essentially one part in
10^8.  This is more than two orders of magnitude less than the amount by
which the inch itself changed during 1959, when it shrank to 2.54 cm from
its former value of 1/0.3937 cm; so there is no point in worrying about the
difference.  The new definition 72.27 pt = 1 in is not only better for
calculation, it is also easier to remember.'

Which, as someone suggested, seems like a good reason to use millimetres.

( al )