Dear List,

Could anyone manage to typeset the following example? Here [] causes an
error "Extra }, or forgotten \endgroup".

    \starttext
    \define\sample{
    \startxtable[]
    \startxtablehead
    \startxrow
    \startxcell 123\stopxcell
    \stopxrow
    \stopxtablehead
    \stopxtable
    }
    \sample
    \stoptext

Thanks in advance.

Best,
Sylvain