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Re: the compatibility issue

Hi:

At 05:49 PM 97/10/23 +0200, Thierry Bouche wrote:

>reading justin's report i cannot second him on the point that
>compatibility of kerning pairs is an issue. I think that the EC fonts
>for instance have enhanced kerning  wrt CM, many kern pairs have been
>added, and some have been fixed (like oj ?--not sure!). I think that
>an alternative math font should have the advance width of Gamma, and
>its skewchar kern fixed. From a general point of vue, i don't think
>that math entities should be automatically kerned, and that kerning
>with punctuation is a bad idea (ideally, punctuation should be typeset
>in text mode). As EC is not isometric to CM, i don't see why math
>fonts should be.

EC is not quite compatible with CM in metrics.  Aside from the new 
and improved kern pairs, generally most advance widths differ by 
1 part in 4096.  Some advance widths are very different, most 
notably the various double quotes.  While this is compensated  
by kern pairs with the boundary character, this presently only works 
with the right boundary character in EC (i.e. no extra space on the
left of quoted material). And no, oj has not been fixed in EC (it has in
EM. :-)
The subscript position for upright Gamma, Upsilon, and Psi have been
fixed in EM (something that can't be done in CM because there those
glyphs  come from text fonts.

So anyway, it is not very useful to try for metric compatability with CM
for math.  I heard from one person that they have avoided 
switching to EC because of the changes in metrics of the text fonts, 
but obviously that decision will not be affected by what you do with
the  math fonts.

>Is the idea that it should be possible to have a set of virtual fonts
>built from CM that allow to emulate perfectly plain or latex209 with
>the future setting? If it is the only need for making glyphs kerned in
>CM live together in M*, i think this one should have an inferior
>priority. Am i wrong?

Berthold Horn