\startxmlsetups xml:testsetups
\xmlsetsetup{test}{test|ab|abc}{xml:*}
\stopxmlsetups
\xmlregistersetup{xml:testsetups}
\startxmlsetups xml:test
\xmlflush{#1}
\stopxmlsetups
\startxmlsetups xml:ab
\writestatus{>>1>> \xmltag{#1}-\xmlcount{#1}{/abc}}{:\xmlindex{#1}{/abc}{1}:}
\writestatus{>>2>> \xmltag{#1}-\xmlcount{#1}{/abc}}{:\xmltext{#1}{/abc}:}
\stopxmlsetups
\starttext
\xmlprocessfile{test}{test.xml}{}
\stoptext
Input is:
<test>
<ab>
<abc>ABC-1</abc>
<abc>ABC-2</abc>
</ab>
</test>