\starttypescript [sans] [arialmt]
    \definefontsynonym [ArialMT][name:arialmt][features=default]
    \definefontsynonym [ArialMTItalic][name:arialitalicmt][features=default]
    \definefontsynonym [ArialMTBold][name:arialboldmt][features=default]
    \definefontsynonym [ArialMTBoldItalic][name:arialbolditalicmt][features=default]
\stoptypescript

\starttypescript [sans] [arialmt]
    \definefontsynonym [Sans][ArialMT][features=default]
    \definefontsynonym [SansItalic][ArialMTItalic][features=default]
    \definefontsynonym [SansBold][ArialMTBold][features=default]
    \definefontsynonym [SansBoldItalic][ArialMTBoldItalic][features=default]
\stoptypescript

\starttypescript [sans] [arialmtblack]
    \definefontsynonym [ArialMT][name:arialmt][features=default]
    \definefontsynonym [ArialMTItalic][name:arialitalicmt][features=default]
    \definefontsynonym [ArialMTBoldItalic][name:arialbolditalicmt][features=default]
    \definefontsynonym [ArialMTBlack][name:arialblack][features=default]
\stoptypescript

\starttypescript [sans] [arialmtblack]
    \definefontsynonym [Sans][ArialMT][features=default]
    \definefontsynonym [SansItalic][ArialMTItalic][features=default]
    \definefontsynonym [SansBold][ArialMTBlack][features=default]
    \definefontsynonym [SansBoldItalic][ArialMTBoldItalic][features=default]
\stoptypescript

\definetypeface[arialmt]     [ss][sans][arialmt]     [default]
\definetypeface[arialmtblack][ss][sans][arialmtblack][default]

\setupbodyfont[arialmt,24pt,ss]
% \setupbodyfont[arialmt,ss,24pt]
% \setupbodyfont[24pt,arialmt,ss]

\starttext
    A {\bfb A} {\bfx A} A\high{A}
\stoptext
