<req>
    <a name="1">
        <a name="2"/>
    </a>
</req>

<r>
    <b id="1">
        <a name="1">
            <a name="2"/>
        </a>
    </b>
    <b id="2">
        <a name="3">
            <a name="4">
                <a name="5"/>
            </a>
        </a>
    </b>
</r>

for $r in $xml2/r/b
where (every $a
        in $r/a
        satisfies $a/@name = $xml1/req/a/@name)
return $r