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Re: [Groff] ASCII Minus Sign in man Pages

From: G. Branden Robinson
Subject: Re: [Groff] ASCII Minus Sign in man Pages
Date: Wed, 3 May 2017 09:04:25 -0400
User-agent: NeoMutt/20170113 (1.7.2)

At 2017-05-02T21:29:39-0400, Doug McIlroy wrote:
> I was previously told that \(mi is the true minus sign. But the
> true minus sign, at least in my mind, must come from the current
> font, so that it comes out right wherever it occurs, even in a
> bold headline like "Fairbanks shivers at -50".

I agree.

> I'll buy Branden's  first assertion, but if + and \- come from the
> current font as they originally did, and \(pl and \(mi come
> from the the current font per the previous paragraph, they
> become redundant.

It wouldn't be the first redundancy in the character escapes:

From groff(7):

       \´     The acute accent ´; same as \(aa.  Unescaped: apostrophe,
              right quotation mark, single quote (ASCII 0x27).
       \`     The grave accent `; same as \(ga.  Unescaped: left quote,
              backquote (ASCII 0x60).
       \_     The same as \(ul, the underline character.

I want to remove some of that overload encouragement in the descriptions
of the unescaped results above, because we have (long had) \[cq] and
\[oq] for single quotation marks, but that's another discussion.

> So I remain confused.

I think it's a confusing issue.  We didn't have Unicode back in the days
of CSTR #54, so the idea that you could get a pile of
mathematically-oriented glyphs out of the same font that you had loaded
to print your running prose was unheard of.

A quick experiment with -Z shows me that groff does still today load the
S [special] font when the \(pl and \(mi character escapes are used.

On my UTF-8 device, of course, this is a no-op.

It's not a no-op on a PostScript device, but I note no _visual_

/F0 10/address@hidden SF 196.51(foo\(1\) quux foo\(1\))72 48 R(plus +)108
84 Q(mathplus)108 100.8 Q/F1 10/Symbol SF(+)2.5 E F0(minus \255)108     
117.6 Q(mathminus)108 134.4 Q F1(-)2.5 E F0 211.235(baz bar)72 768 R(1) 
222.615 E 0 Cg EP

On what devices do we expect a visual difference?


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