Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!intercon!news
From: amanda@mermaid.intercon.com (Amanda Walker)
Newsgroups: comp.lang.postscript
Subject: Re: ruler.ps - an inch/point ruler of your very own
Message-ID: <1990Jan15.183143.7677@intercon.com>
Date: 15 Jan 90 18:31:43 GMT
References: <21772@uflorida.cis.ufl.EDU> <1990Jan14.180821.18711@trigraph.uucp>
Sender: @intercon.com
Reply-To: amanda@mermaid.intercon.com (Amanda Walker)
Organization: InterCon Systems Corporation, Sterling, VA
Lines: 33

In article <1990Jan14.180821.18711@trigraph.uucp>, bruce@trigraph.uucp (Bruce
Freeman) writes:
> The great thing about points is that there are so many of them to the inch.
> PostScript has decided that there are exactly 72 to the inch but the industry
> standard is generally that there are 72.3 points to the inch.

It's actually even worse, especially if you take European conventions
into account.

"Conventional" Amrican		72.27 ppi
PostScript and some others	72 ppi
Didot point			67.54 ppi

And then there's the pica (12pt), which is therefore sometimes 1/6th of an
inch, and sometimes 1/6.022th of an inch, the cicero, which is 12 didot
points, ...

For example, I usually use TeX to format things, and so when I ask for
a 10pt font in TeX, it turns into a 9.96264 point font in PostScript.
There is very little visible difference, but my documents take a while to
start up, since there usually aren't any 9.96264 point fonts in
the font cache :-).

"The nice thing about standards is that there are so many to choose from,"
as someone whose name I have temporarily forgotten once said...

Amanda Walker
InterCon Systems Corporation

(Our news & mail machine swallowed its tongue last week, so some mail may
have bounced or evaporated, and I've missed a week of news...).

--