Path: utzoo!yunexus!geac!syntron!jtsv16!uunet!husc6!mailrus!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!killer!dcs!wnp
From: wnp@dcs.UUCP (Wolf N. Paul)
Newsgroups: comp.text
Subject: Re: Definition of Point
Message-ID: <217@dcs.UUCP>
Date: 13 Oct 88 11:43:20 GMT
Article-I.D.: dcs.217
References: <2610015@hpsal2.HP.COM> <30767@bbn.COM>
Reply-To: wnp@dcs.UUCP (Wolf N. Paul)
Organization: DCS, Dallas, Texas
Lines: 39

In article <30767@bbn.COM> cosell@BBN.COM (Bernie Cosell) writes:
* In article <2610015@hpsal2.HP.COM> morrell@hpsal2.HP.COM (Michael Morrell) writes:
* }Does anyone know the exact definition of "point" (as in a 12-point font)?
* 
*   POINT SYSTEM: The system by which all typographic manterial is manufactured
*   to sizes which are exact multiples of a point.  The English and American
*   point is 0.0138 in. or more accurately 72 points = 0.9966 inch.  The Didot
*   point used on the Continent is slightly larger, it is 0.376 mm, English
*   point 0.351 mm.
*       -from {\it Basic Typography} by John R. Biggs
* 
* Note that this is a *design*size* when you're using it to refer to a font.
* There may well be *nothing* in the font itself that you can measure that is
* actually "12 points" long or high or anything else.  

1. The English point referred to above is often called the PICA POINT in
   contrast to the continental Didot point, which is sometimes referred to
   (at least in German typography, and when contrasting with Pica) the 
   CICERO point. This refers to the traditional names for the respective
   12-point size, which in the Anglo-American system is called PICA, and in
   the Didot System, in German at least, CICERO.

2. While the above comment about there not necessarily being anything measurable
   in a font, generally pointsize is considered to refer to the sum of x-height
   (i.e. the height of the lower case x and by inference of most l.c. chars.),
   descenders, and ascenders or (cap height - x height), whichever is larger.

   I am making this comment, because I have come across several DTP books and
   programs which measure point size just on the cap height, and that leads to
   specs and type sizes which differ from the standard, leading to much 
   confusion.

3. Finally note that the relationship of x-height and cap height determines the
   visual size of a font -- i.e. HP Softfonts TmsRmn 12pt looks much bigger
   than Knuth's TeX Computer Modern Roman 12pt., because of the HP fonts' larger   lower case characters.
-- 
Wolf N. Paul * 3387 Sam Rayburn Run * Carrollton TX 75007 * (214) 306-9101
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