# [texhax] TeX Queries (2)

Reinhard Kotucha reinhard.kotucha at web.de
Fri Jul 13 22:30:41 CEST 2012

```On 2012-07-13 at 14:50:54 -0400, Barbara Beeton wrote:

> regarding multiple quotes,
>
> On Fri, 13 Jul 2012, Reinhard Kotucha wrote:
>
>     I vaguely remember that double quotes are ligatures in TeX.  This
>     could probably explain why both examples yield different results.
>
> for the computer modern fonts, double quotes
> are definitely ligatures.  so two quotes in
> a row (either leading or trailing) will
> produce a "designed" double quote.  thus,
> if three quotes are input together as ```,
> tex (using computer modern) will interpret
> the first two as a double, and only one
> remains.  thus, if a single quote is to be
> first, it has to be isolated in braces.
>
> i can't speak for fonts that don't have tfm
> files; presumably any font for which a tfm
> file has been created will have been adjusted,
> if necessary, to follow the tex conventions.
> but i'm sure it can't be guaranteed for
> "system" fonts as used by xetex or luatex.

I used pdftex for testing.  The only difference between pdftex and
Knuth's tex in this respect is the output format.  Regarding fonts, in
TeX Live both engines are using the Blue Sky Research Type 1 fonts.
It would be strange if the tfm files are different from Knuth's,
especially because they are preloaded in the format files, which are
created from exactly the same source in both cases.

But Paul Isambert said that according to the TeXbook, the second line
in the following file requires \thinspace instead of braces.  Paul, do
you remember the page number?

---------------------------
{`}`` bla bla ''{'}
\par
``{`} bla bla {'}''
\bye
---------------------------

Regards,
Reinhard

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