\starttext

\definefontfeature[one]  [default]
\definefontfeature[two]  [default][itlc=yes]
\definefontfeature[three][default][itlc=2]
\definefontfeature[four] [default][itlc=10]


\def\TestMe#1%
  {\definefont[test][SerifItalic*#1]
   \setbox\scratchbox\hbox{A short sentence with a {\test italic} word.}
   \dontleavehmode\hbox to 3cm{\the\wd\scratchbox\hss} \box\scratchbox\par
   \setbox\scratchbox\hbox{A short sentence with a {\test italic\/} word.}
   \dontleavehmode\hbox to 3cm{\the\wd\scratchbox\hss} \box\scratchbox\par}

\TestMe{one}
\TestMe{two}
\TestMe{three}
\TestMe{four}

\stoptext
