% characters.filters.utf

\ctxlua{characters.filters.utf.collapsing=false}

\definefontfeature[tex][mode=node,script=latn,ccmp=yes,calt=yes]

\starttext
    \showotfcomposition{file:TeXCalt.otf*tex at 20pt}{1}{TEX}
    \page
    \showotfcomposition{file:TeXCalt.otf*tex at 20pt}{1}{TÈX}
    \page
    \showotfcomposition{file:TeXCalt.otf*tex at 20pt}{1}{TÈ̀̀̀X}
\stoptext
