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Re: Units of measurements

From: Frank Boumphrey <bckman@ix.netcom.com>
Date: Mon, 6 Apr 1998 13:59:57 -0700
To: "John Ky (HxG)" <z2206460@student.unsw.edu.au>, "STYLE" <www-style@w3.org>, "Todd Fahrner" <fahrner@pobox.com>
Message-ID: <01bd619e$f4dd1ae0$9bacdccf@uspppBckman>
"You must be confusing em with pica"

No. I have (inherited from my uncle Hugh Williamson, who wrote one of the
definitive books on typography), a ruler called an 'em' ruler. An em in
typesetting became standardized at 6 to an inch, although as you pointed out
originally it was the width of the square letter 'm'.

It doesnt really matter though because we all agree what it means in CSS<g>

-----Original Message-----
From: Todd Fahrner <fahrner@pobox.com>
To: Frank Boumphrey <bckman@ix.netcom.com>; John Ky (HxG)
<z2206460@student.unsw.edu.au>; STYLE <www-style@w3.org>
Date: Monday, April 06, 1998 9:32 AM
Subject: Re: Units of measurements

>Thus spake Frank Boumphrey:
>>      em takes on a different meaning in CSS to the  usual typographic
>>term. In Typography, 6em's=1 inch,
>You must be confusing em with pica. A pica is 12 points. There are six of
>them in an inch. Only in a 12-point font is a pica equivalent to an em. As
>for em as a "usual typographic term", there's no end of debate on the
>connection to the letter em. Jan Roland Eriksson has produced a nearly
>exhaustive treatment here:
>http://home2.swipnet.se/%7Ew-20547/stylework/typograph1-en.html#Ch23 ...
>yet he disputes any historical connection to the letter M. I've heard
>otherwise, and will recycle a little ascii art from usenet:
>It's my understanding that there is a relationship to the letter M, or
>rather, to the chunk of metal[1] upon which the raised face of the letter
>once typically sat:
>   _________________
>   | |\    /| ||   |\
>   | | \  / | || . | \
>   | |  \/  | || | | |
>   | |      | || | | |      ---> "iM"
>   |          ||   | |
>   ----------------- |
>    \           \\  \|
>     \           \\  \
>      ------------ ---
>Unlike most of the letters, which sat on narrower chunks of metal, the M's
>was square, at least for the most common designs of the letter M at an
>early point in printing history[2] (this was somewhat wider than current
>fashion has it). Thus the M's width served as a handy horizontal unit
>equivalent to the height of all the characters' chunks; i.e., for the
>nominal font size. "Em" came to mean, metonymically, this latter thing,
>even after the letter M began to be designed more narrowly.[3]
>[1] http://www.tiro.com/lead.gif
>[2] http://www.tiro.com/aen_rom.html
>[3] http://www.tiro.com/pla_rom.html
>>      -----Original Message-----
>> From:      John Ky (HxG) <z2206460@student.unsw.edu.au>
>>      Also, the      ex unit turned out     to be slightly less than the
>>width of the 'x'     character.
>As Frank noted, ex is universally misimplemented - as .5em. Last time I
>checked, NS also gave too large a value for em; i.e., representing 1 em as
>something more like 1.1em.
>Todd Fahrner
Received on Monday, 6 April 1998 13:56:30 UTC

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