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Re: [Groff] Unexpected output for \(a~
From: |
Anthony J. Bentley |
Subject: |
Re: [Groff] Unexpected output for \(a~ |
Date: |
Fri, 20 Mar 2015 07:48:23 -0600 |
Ingo Schwarze writes:
> Hi Carsten,
>
> Carsten Kunze wrote on Fri, Mar 20, 2015 at 01:07:55PM +0100:
>
> > in groff_char.7 it is specified that U+0303 is output for \(a~ but
> > actually U+007E is output. Why does the output (of nroff -Tutf8)
> > differ from the specification?
>
> It seems to me that you misread the documentation. It reads:
>
> Accents
> -------
>
> The composite request is used to map most of the accents to non-spacing
> glyph names; the values given in parentheses are the original (spacing)
> ones.
>
> Output Input PostScript Unicode Notes
> --------------------------------------------------------------------------
> ~ \[a~] tilde u0303 (u007E) tilde accent
>
> That means you get U+007E when using the character directly -
> which certainly makes sense.
>
> The combining (non-spacing) variant shown before the parenthesis
> only applies in the context of the .composite request.
When looking at this, I learned something new: U+007E is *not* the
spacing equivalent to U+0303; U+02DC is. This effect is visible in
groff's PDF output. In fact, an ASCII tilde gets replaced with a U+0303
in PDF output, and must be escaped as \(ti to output a straight ASCII
tilde. However, UTF-8 nroff(1) output seems to output U+007E for both
\(a~ and ~ inputs.
--
Anthony J. Bentley