$ pm_xml_db_diff.pl
<Data>
  <Root1>
    <TBLA>
      <MODIFIED>
        <KEY name="KEY1">
          <COLA>
            <newvalue>B</newvalue>
            <oldvalue>A</oldvalue>
          </COLA>
          <COLB>
            <newvalue>E</newvalue>
            <oldvalue>D</oldvalue>
          </COLB>
        </KEY>
        <KEY name="KEY3">
          <COLX>
            <newvalue>N</newvalue>
            <oldvalue>M</oldvalue>
          </COLX>
        </KEY>
      </MODIFIED>
      <NEW1>
        <KEY>KEY6</KEY>
      </NEW1>
      <NEW2>
        <KEY>KEY9</KEY>
        <KEY>KEY10</KEY>
      </NEW2>
    </TBLA>
  </Root1>
  <Root2>
    <TBLB>
      <MODIFIED>
        <KEY name="KEY4">
          <COLD>
            <newvalue>B</newvalue>
            <oldvalue>A</oldvalue>
          </COLD>
          <COLX>
            <newvalue>N</newvalue>
            <oldvalue>M</oldvalue>
          </COLX>
        </KEY>
      </MODIFIED>
      <NEW1>
        <KEY>KEY7</KEY>
      </NEW1>
    </TBLB>
  </Root2>
  <Root3>
    <TBLC>
      <MODIFIED>
        <KEY name="KEY5">
          <COLD>
            <newvalue>B</newvalue>
            <oldvalue>A</oldvalue>
          </COLD>
        </KEY>
      </MODIFIED>
      <NEW1>
        <KEY>KEY8</KEY>
      </NEW1>
      <NEW2>
        <KEY>KEY11</KEY>
      </NEW2>
    </TBLC>
  </Root3>
</Data>