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on skewchar = space


I've just grep'ed through the mail archives concerning the origin of
the convention to use of slot 0 as the skewchar.  It appears to me now
that there was no technical reason for choosing this particular slot,
just the intention to use a character not intended for typesetting
and simplicity:

  Date: 04 Aug 1993 15:48:32 -0400 (EDT)
  From: Michael Downes <MJD@MATH.AMS.ORG>
  Subject: Re:  The skewchar.
  To: ziegler@micky.zdv.Uni-Mainz.DE
  [...]

  Interesting also, that TeX does
  not scale \fontdimen 1. Thus another approach for math fonts might be
  to use fontdimen1 to give the value of \skewchar, and use the ratio
  height/width of skewchar to give the slant per point. This is assuming
  that the font position \skewchar does not contain a real character
  intended for typesetting---which is a good idea anyway.

  But actually, it occurs to me now, a better approach is to mandate
  always \skewchar = 0 for math fonts and leave font position 0 empty.
  This solves the problem of having to find a suitable character for
  \skewchar that will never naturally occur in combination with the
  characters for which skews are specified. If there is other extra
  information needed for a math font, it could be encoded in the height,
  width, depth of character 0.

  - - - - - - - - 

  From alanje@cogs.susx.ac.uk Fri Aug  6 14:23:24 1993
  Date: Fri, 6 Aug 93 14:03 BST
  From: alanje@cogs.susx.ac.uk (Alan Jeffrey)
  To: math-font-discuss@cogs.susx.ac.uk

  >But actually, it occurs to me now, a better approach is to mandate
  >always \skewchar = 0 for math fonts and leave font position 0 empty.

  I'd go for this.  Glyph zero is `acute' in T1, and I doubt many Cork
  fonts include kerning with acute, so we're probably OK.

  - - - - - - - - 

That's about all there is to it in the archives.  Subsequent versions
of Justin's papers of mid-August 1993 listed "skewchar in postion 0" 
as a given requirement without any further explanation or discussion.


So much for the history.  If no one objects due to technical reasons,
I'd suggest to follow Matthias most recent suggestion to use \skewchar
= space glyph (32) and free the slot 0 for normal use in font tables.

Cheers, Ulrik.