Hello,

I have a bunch of simple fonts for Arabic/Persian.  These fonts lack Latin
characters, etc., so I use fallbacks to work with them.

I just noticed that \high does not work with them, and have not been able
to pinpoint the issue.  See the MWE below.


\starttypescript [serif][samim][name]
  \definefontsynonym[Serif][Samim]
\stoptypescript

\definetypeface [myfont][rm] [serif][samim][default]
\setupbodyfont [myfont]

\starttext
%\definedfont[Samim*arabic]
۱۲۳\high{۴}۵۶.
\stoptext


I am using Persian digits because the font lacks Latin digits as I
mentioned.  If I use the \definedfont approach, I don't see the character ۴
(argument of \high) at all.  With the typescript approach, the same
character *is* typeset but is *not* raised; it appears on the baseline but
with smaller size.

Any ideas why this is happening?  Could it be that some parameters, for
instance, \exheight are not properly set/read for this font?  Actually, I
looked at the non-math fontdimens in syst-fnt.mkiv, and everything except
\slantperpoint (expected) and \exheight (awkward) is non-zero.  I don't
know where \exheight comes from—perhaps from the height of glyph for 'x',
which the font lacks—however, \emheight is 12pt, although the font also
lacks a glyph for 'm'.

I am also attaching the font in case that helps.

Thanks,
Hossein