[NTG-context] Unexpanded texdefinition produces “Undefined control sequence”

Hi, the following example produces an “Undefined control sequence” error. If \def is used instead of \starttexdefinition then there is no error. Why? \starttexcode \installcommandhandler{foo}{foo}{foo} \appendtoks \setuevalue{start\currentfoo}{\foo@start[\currentfoo]}%% \setuevalue{stop\currentfoo }{\foo@stop}%% \to\everydefinefoo \starttexdefinition unexpanded foo@start [#1] \stoptexdefinition %% works %% \unexpanded\def\foo@stop{} %% produces undefined control sequence error \starttexdefinition unexpanded foo@stop \stoptexdefinition \stoptexcode \definefoo [myfoo] \starttext \startmyfoo Foobar \stopmyfoo \stoptext Marco