BuGlessRB/remixml

 <set var="_.a">abc</set>
 <set var="_.b">xyz</set>
 A1
 <cache key="a" shared="aha"
  >1B1<nocache>X&_.b;Y
   <set tag="yes"></set>
   <yes></yes>
  </nocache>h&_.a;C1<nocache>X&_.b;Y</nocache>1</cache>
 <set var="_.b">pqr</set>
Yes
 <cache key="a" shared="aha"
  >1b1<nocache>X&_.b;y</nocache>h&_.a;C1<nocache>x&_.b;y</nocache>2</cache>
 M1