[PLUG] Re: css questions
Ronald Chmara
ron at Opus1.COM
Sat Jul 30 02:58:54 UTC 2005
On Jul 29, 2005, at 6:27 PM, Wil Cooley wrote:
> On Fri, 2005-07-29 at 18:16 -0700, Rich Shepard wrote:
>> On Fri, 29 Jul 2005, Michael Rasmussen wrote:
>>> 1 em is the size of a character.[1]
>> It's actually the size of an 'em-dash' which is entered in TeX as
>> '--'.
> Actually, and em-dash is a dash that's the width of an 'M', as Ali just
> mentioned, not the other way around.
<pedantic level="excessive">
That's a popular way to think about it (em and en dashes being 'M' and
'N' width in a given font), however, that's not entirely the whole
story... some fonts have no letter 'M' or 'N', and thus, the meaning
has changed over the years. An em-dash is now typically one "em" unit
in length, regardless of the size (or presence) of the letter 'M' in a
given font. An en is half of an em.
So, if an em unit is not actually fixed to an 'M' character, what
determines it's size? It's fixed to the size of an imaginary box which
all characters in a given font can fit into. So if a font had a larger
letter in it than a letter 'M', the em unit for that font would be the
size of the largest letter, horizontally as well as vertically (as not
all character systems are horizontal).
See:
<http://en.wikipedia.org/wiki/Em_%28typography%29>
<http://en.wikipedia.org/wiki/Dash>
Of course, for stylistic reasons, typographers do create fonts where an
em-dash is *not* the size of the em, and the en-dash is *not* the size
of an en or even half of an en, but the em size is constant, with an en
being half of an em.
</pedantic>
I'm sure you were all dying to know that.
-Bop
--
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