[XeTeX] font selection debugging

[Vladimir Volovich]

"JK" == Jonathan Kew writes:

 JK> In general, rather than \font\xxa="ArTarumianGrqiNor_U
 JK> BoldItalic/I/ ICU", I would suggest
 JK> "\font\xxa="ArTarumianGrqiNor_U/BI/ICU"; in other words, use the
 JK> family name and style modifiers in preference to a full name. (But
 JK> this may not always work as it should, especially if the family
 JK> doesn't have the usual collection of members.)

this font was produced by the fontspec package. the latex source file
contained

\setmainfont[BoldFont=ArTarumianGrqiNor_U BoldItalic,ItalicFont=FMBF Notr]{ArTarumianGrqiBardzr_U}

and fontspec.sty contains this code:

    \@tempswatrue
    \ifzf at nobf\@tempswafalse\fi
    \ifzf at noit\@tempswafalse\fi
    \if at tempswa
      \ifx\zf at bfit\@empty
        \ifx\zf at bf\@empty
          \ifx\zf at it\@empty
            \zf at make@font at shapes[\zf at fontname]{/BI}
              {\bfdefault}{\itdefault}{\zf at font@feat\zf at bfit@feat}%
          \else
            \zf at make@font at shapes[\zf at it]{/B}
              {\bfdefault}{\itdefault}{\zf at font@feat\zf at bfit@feat}%
          \fi
        \else
          \zf at make@font at shapes[\zf at bf]{/I}
            {\bfdefault}{\itdefault}{\zf at font@feat\zf at bfit@feat}%
        \fi
      \else
        \zf at make@font at shapes{\zf at bfit}
          {\bfdefault}{\itdefault}{\zf at font@feat\zf at bfit@feat}%
      \fi
    \fi

and the lines

          \zf at make@font at shapes[\zf at bf]{/I}
            {\bfdefault}{\itdefault}{\zf at font@feat\zf at bfit@feat}%

are those which prodiced the \font with name "ArTarumianGrqiNor_U BoldItalic/I/ICU"

and apparently on two different PCs with the same fonts installed
this produces different results:

"ArTarumianGrqiNor_U BoldItalic/ICU".
"ArTarumianGrqiNor_U Bold/ICU".

so i wonder

 * if code in fontspec is correct (why is it trying to add "/I"
   when i explicitly specify the BoldFont name?),

 * why the results of \font\x="ArTarumianGrqiNor_U BoldItalic/I/ICU"
   are different on two PCs

Best,
v.