[Gllug] font annoyance of the day

Tethys sta296 at astradyne.co.uk
Sun May 20 16:05:28 UTC 2007

Chris Bell writes:

>The type base was measured in Points, (described as 1/72 inch in Britain
>but probably something similar in metric).

#ifdef FONT_GEEK

Not so simple, I'm afraid. There have been various definitions of the
point, each slightly different in size to the others. Didot's point,
for example, was exactly 1/72nd of a pouce (the "French inch", which
is around 6.5" larger than an Imperial inch), For largely pragmatic
reasons, some printers varied that to a greater or lesser extent.
But their definitions of the point were mostly based around fractions
of an inch (or in some cases, feet). Except for some which were based
around fractions of metric measurements instead.

Then comes variation in the definition of length. Quite aside from
the difference between the Imperial foot and the French royal foot
(and their corresponding inches), the definition of the Imperial inch
varied, even after the rest of the world had gone metric, before finally
settling down to a fixed size in 1959. The printer's point also settled
down to a value of around 1/72.27 inches.

Later, the PostScript imaging model defined a point to be exactly 1/72",
which was chosen for its similarily to the traditional printer's point.
In part due to the success of PostScript, the typesetting world slowly
adopted this new definition of the point, leading to the situation today
where a point is almost universally considered to be exactly 1/72".

#endif /* FONT_GEEK */

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