1. List All ACs in xml document
   result should be:
        AC desc AC=CCC, CL=CCC
        AC desc AC=AAA, CL=CCC # these are the <Desc> element just below start tag <AC> also need to be able to update the text if requested.

2. List all AIs in a given AC, eg AC=CCC
   result should be:
        AI desc AI=BBB, AC=CCC
        AI desc AI=XXX, AC=CCC

3. List all <ID> nodes in a given <AI n="XXX">
   result should be:
     a.  ID desc ID=XXX, AI=BBB, AC=CCC
         What XXX ID
         ID_XXX

     b.  ID desc ID=ZZZ, AI=BBB, AC=CCC
         What ZZZ ID
         ID_ZZZ

The based on the user selection, I need to update the requested text within an element or add a whole new node. 


<World n="earth" >
  <Space n="XXX">
    <CL n="XXX">
      <Desc>Class description</Desc>
      <Other/>
      <AC n="AAA" set="n">
        <Desc>AC desc AC=AAA, CL=CCC</Desc>
      
        <AI n="AAA" set="n">
          <Desc>AI descr AI=AAA, AC=AAA</Desc>
          <ID n="AAA" set="y">
            <Desc>ID desc ID=AAA, AI=AAA, AC=AAA</Desc>
            <What>What ID=AAA AI=AAA, AC=AAA</What>
            <AR>ID_aaa</AR>
          </ID>
            
          <ID n="BBB" set="y">
            <Desc>ID desc ID=BBB, AI=AAA, AC=AAA</Desc>
            <What>What ID=BBB AI=AAA, AC=AAA</What>
            <AR>ID_bbb</AR>
          </ID>
        </AI>
      
        <AI n="BBB" set="y">
          <Desc>AI desc, AI=BBB, AC=AAA</Desc>
          <ID n="AAA" set="y">
            <Desc>ID desc ID=AAA, AI=BBB, AC=AAA</Desc>
            <What>What AAA ID=BBB, AI=BBB, AC=AAA </What>
            <AR>ID_bbb</AR>
          </ID>
        </AI>
      </AC>

      <AC n="CCC" set="y">
        <Desc>AC desc ACC=CCC, CL=CCC</Desc>
        <AI n="AAA" set="n">
          <Desc>AI desc AI=BBB, AC=CCC</Desc>
          <ID n="AAA" set="y">
            <Desc>ID desc ID=AAA, AI=AAA, AC=CCCC</Desc>
            <What>What AAA ID=AAA, AI=AAA, AC=CCC </What>
            <AR>ID_aaa</AR>
          </ID>
        </AI>
      
        <AI n="XXX" set="n">
          <Desc>AI desc AI=XXX, AC=CCC</Desc>
          <ID n="XXX" set="y">
            <Desc>ID desc ID=XXX, AI=BBB, AC=CCC</Desc>
            <What>What XXX ID </What>
            <AR>ID_XXX</AR>
          </ID>

          <ID n="ZZZ" set="y">
            <Desc>ID desc ID=ZZZ, AI=BBB, AC=CCC</Desc>
            <What>What ZZZ ID </What>
            <AR>ID_ZZZ</AR>
          </ID>

        </AI>
      </AC>

    </CL>
  </Space>
</World>