\starttypescript [sans] [aslantregular] [name]
	\definefontsynonym [Sans]           [a]
	\definefontsynonym [SansItalic]     [aslant]
%    \definefontsynonym [Sans]		[name:aregular] 	[handling=pure]
%    \definefontsynonym [Sans-Italic]	[name:aslantregular] [handling=pure]
\stoptypescript

%\definetypeface [a] [ss] [sans] [a]
\definetypeface [aslantregular] [ss] [sans] [aslantregular]

\setupbodyfont[aslantregular, 270pt]
\starttext

\sans{ABCDEa}

\italic{ABCDEa}

\stoptext