[texhax] The \/ control sequence

[Reinhard Kotucha]

On 25 May 2010 Philip G. Ratcliffe wrote:

 > > I've discovered one use for the \/ macro i.e. used in transition from 
 > > a \sl or \it to \rm.
 > 
 > As I remember, that IS its true use.
 > 
 > > I understand it's something to do with the spacing between the
 > > last \it or \sl char and the first \rm char. A few keywords as to
 > > the real impact of the macro would be really appreciated.  Are
 > > there other uses for the \/ control sequence?
 > 
 > Yes, it simply adds a little more space to "look better". That is,
 > the spacing between words in \it or \sl is reduced w.r.t. \rm
 > because the space too is actually slanted, as it were.  So a touch
 > more is needed when followed by a non \it or \sl.
 > 
 > It could be used anywhere where slightly more space might be
 > desirable, but to be kosher one might prefer \, or some more
 > specific \hspace{...} in other situations.

I fear that it can't be used for anything else but italic correction.
I assume that its horizontal width is determined from the TFM file
(via a fontdimen parameter) of the font you are currently using.
Thus, if you are currently using an upright font, \/ has no effect.

With an upright font (cmr10) I don't see any difference between
foo\/bar and foobar.

Paul, your assumption is absolutely correct.  The italics correction
is needed because TeX is not aware of the actual shape of a particular
glyph but only about its width at the baseline.  Hence, additional
information is needed if a slanted glyph is followed by an upright
one.  Therfore the amount of slanting is mentioned in the TFM file.
BTW, Adobe Type 1 fonts also contain a variable "ItalicAngle",
obviously for the same reason.

Regards,
  Reinhard

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