Tricky problem (I think):
I want to change the tag with a specific attribute and value: <div class="THD"> to <h1 class="THD">.
The closing <\div> tag belonging to the respective tag also needs to change.

Does anyone know about a tool that can help me do that (without much manual editing).

I have a large html document structured like this (simplified):

Code:
<div class="MAIN" id="B01-C1">
<div class="CHSO">
<div class="THD">
<div class="HNUM">Chapter 11</div>
<div class="HD">Freedom</div>
</div>
</div>
<a name="PG72"> </a><div class="page"><div>P.53</div></div><br clear="all">
<div class="TBD">
<div class="TLV1" id="B0142943">
<div class="HD">OVERVIEW/div>
<div class="P">Aung San Suu Kyi, the Burmese democracy leader, called for a “non-violent revolution” today as she began the task of re-establishing herself as the leader of a political party after seven years of house arrest.</div>
</div>