W3C home > Mailing lists > Public > www-style@w3.org > February 2000

RE: What's an em

From: Just van Rossum <just@letterror.com>
Date: Tue, 1 Feb 2000 17:07:44 -0500 (EST)
Message-Id: <l0310280bb4bd05087042@[]>
To: Karlsson Kent - keka <keka@im.se>, www-style@w3.org, "'www-font@w3.org'" <www-font@w3.org>
You can discuss this 'till you drop, you're not going to get a definitive
answer. The fact that you already found so many (contradicting) definitions
only means one thing: there is no true definition.

However, the only *useful* definition is that of point size, since it's the
only one that's exact: eg. TrueType has a value called unitsPerEm. If a
font has 1000 units per em, it means that when set at 12 points, 1000 units
in design space are 12 points in user space. That's all there is to it.

(Don't ever start measuring letters: it's a dead end, since it's not exact
by definition. Take two simple lowercase letters 'o', one light, one very
heavy. Scale them so they are exactly the same height. View at small size.
The bold one looks smaller.)

Received on Thursday, 3 February 2000 10:21:17 UTC

This archive was generated by hypermail 2.3.1 : Monday, 2 May 2016 14:26:53 UTC