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Re: What's an em (was RE: Units, font sizing, and zoom suggestion for CSS 3)

From: David Lemon <typenerd@slip.net>
Date: Tue, 1 Feb 2000 14:18:19 -0500 (EST)
Message-Id: <l03130305b4bcda97e194@[]>
To: www-style@w3.org, "'www-font@w3.org'" <www-font@w3.org>
At 6:21 PM +0100 1/31/00, Karlsson Kent - keka wrote:
> In TrueType an em is undefined (it's up to each typeface designer
> what it "is").  This *so called* "em" should be left as something
> INTERNAL to a font...

While TrueType does not explicitly state that the em is euqivalent to the
type size, that definition is implicit. TrueType allows the
designer/producer to set the number of units per em. This has the effect of
establishing the font's coordinate space, because the em is a constant
(while units are not).

There are many typesetting systems I've not had the priviledge(?) of
working with. But in more than twenty years, I've not come across any
system other than the old Monotype casters which defined an em as other
than the type size. I fail to see any advantages to doing so.

- David Lemon
Received on Thursday, 3 February 2000 10:26:52 UTC

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