...

...

Should'nt \arg{bla} be \type{{bla}}?

I can't give you a satisfying answer for this, but

Should'nt \expandafter\type\expandafter{\arg{bla}} be \type{{bla}}?

gives

Should?nt \dohandlemathtokenarg{bla} be {bla}?

(so I guess the answer is probably no)

\arg is one of the verbatim macros, like \type, \typ, \tex and is describte in 'cont-enp.pdf' on page 101. The description looks a bit incomplete: (the command encloses the text with .) (Can someone, with the right to do that, add this to the list of typos, please?) The definition of \arg is in 'core-ver.tex' and copying this in a separate file works as expected: \starttext \unprotect \def\setgroupedtype {\let\currenttypingclass\??ty \initializetype \catcode`\{=\@@begingroup \catcode`\}=\@@endgroup} \unexpanded\def\arg{% \groupedcommand{\setgroupedtype\leftargument}{\rightargument}} \protect \arg{bla} \stoptext So there must something be damaged. Wolfgang