EM fonts character spacing problem

[jarmo.niemela at suomi24.fi]

On Thu, 4 Dec 2003 23:39:42 +0200 I wrote:
> I get much wider gaps before commas and between the single quotes
> when using EM fonts (\usepackage{em}) compared to when using
> ae fonts (\usepackage{ae}). Especially bad is "$V$," which outputs
> something like "V ,". Also "\pageref{page one}," produces much more
> space between the number and comma than does the following "1,".
> The ae fonts don't produce these wide gaps and neither do bitmapped
> ec fonts.
>
> Is there something wrong with my installation, or is this a more
> common problem/feature of the EM fonts?
>

Before I post my questions to comp.text.tex, here's a partial answer, if
anybody is interested.

Firstly, there is nothing wrong with my installation of Y&Y EM fonts. The
above mentioned problem can be seen for example in Berthold K.P. Horn's TUGboat
article, where he introduces these EM fonts! (TUGboat, Vol. 19 (1998), No.
1; available from http://www.tug.org/TUGboat/Articles/tb19-1/tb58horn.pdf)
See the last line of the first paragraph of that article: "or `ATM' form.",
which is produced typing something like "or `{\small ATM}' form." In the
pdf output there is clearly too much space between the quotes and ATM. Compare
this to `PostScript' on the previous line.

This bug/feature is related to kerning with respect to the boundary character.
As Mr. Horn in his article explains, the EM fonts add extra kerning between
the boundary character (space) and single and double quotes, among others.
All is well If I type something like
<space>`some text'<space>
the output will be
<space><kern>`some text'<kern><space>
as it should be. There is no extra space between ` and s  or  t and '.
But if I write
<space>'{some text}'<space>
the output is
<space><kern>`<kern>some text<kern>'<kern><space>
which leaves disturbing gaps between the quotes and the text being quoted.
This error is produced by any grouping, be it {}, $$, \emph{} or something
else.

This problem can be solved by removing these extra kernings from EM font
metrics files (there are 57 of them). If somebody has done this already,
please let me know. Or maybe there is a better solution? I don't know enough
about fonts or TeX to give more answers.

--
Jarmo Niemelä
research assistant
Department of Mathematics, Statistics, and Philosophy
University of Tampere
Finland

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