RE: Difference between EM QUAD and EM SPACE

From: Gregg Reynolds (
Date: Thu Jul 27 2000 - 21:35:41 EDT

> -----Original Message-----
> From: Edward Cherlin []
> Sent: Wednesday, July 12, 2000 1:23 AM
> To: Unicode List
> Subject: RE: Difference between EM QUAD and EM SPACE
> At 2:09 AM -0800 7/11/00, Roozbeh Pournader wrote:
> >On Mon, 10 Jul 2000, Jonathan Coxhead wrote:
> >
> > > In TeX, the difference is that an EM QUAD (\qquad) and
> an EN QUAD
> > > (\quad) provide spaces that are legitimate breakpoints
> for lines within a
> > > paragraph; while EM SPACE, EN SPACE (\enspace) and THIN
> SPACE (\thinspace)
> > > produce horizontal space that cannot cause a line-break.
> Very close, except for the size of the quads.
> >I don't think so. I remember thatn in TeX, \quad was an an
> em quad, and
> >\qquad a double em quad. Would someone look at a good source
> for that?
> >
> >--roozbeh
> Correct.

Yep. Those lurkers without access to traditional typographic manuals will
(I hope) find the following fun or at least nonannoying:

- TeX's abstractions are explicitly modeled on handset letterpress printing;

- Traditionally the em (a/k/a "mutton", "molly", "mary") quad (=quadrat) was
the square of the body size of the font; this does _not_ mean that the "set
width" of the M sort (traditional term for a particular lead letter thingee
or packet of such thingees) is equal to its body height. For any particular
letterface (i.e. set of punches) body height and set width could be just
about anything, for each sort, in principle;

- The en (a/k/a "nut") quad was half the width of the mutton;

- Narrower spacing sorts were called "3 to the em", "4 to the em", "5 to the
em" etc., obviously representing divisions of the mutton quadrat. I don't
believe such sorts were called "spaces". Various thin spaces were skinny
little pieces of metal, lead or brass, use to make minute adjustments to

- Wider spacers were called "2 em", "3 em", etc.

- "mutton", "nut", etc. were so called to avoid misunderstandings in a noisy
print shop.


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