\startbuffer[example]
<something>
    <sometex>weird</sometex>
</something>
\stopbuffer

\startbuffer[weird]
    \color[red]{Looks red to me!}
\stopbuffer

\startxmlsetups xml:mysetups
    \xmlsetsetup{#1}{*}{xml:*}
\stopxmlsetups

\xmlregistersetup{xml:mysetups}

\startxmlsetups xml:something
    \blank \relax [start something] \blank
    \xmlflush{#1}
    \blank \relax [stop something] \blank
\stopxmlsetups

\startxmlsetups xml:sometex
    \processTEXbuffer[\xmlflush{#1}]
\stopxmlsetups

\starttext
    \xmlprocessbuffer{main}{example}{}
\stoptext
