gistfile1.xml

<!-- IN page.xml -->


<!-- this defines a "content block" in the layout of the page. -->
<block name="Foo">
  <!-- yada yada yada -->
</block>


<!-- in ANY OTHER xml file -->

<reference name="Foo">
    <!-- anything can happen here. You can add additional things to blocks. You can remove them. IT'S A MAD HOUSE! -->
    <!-- I'm pretty sure you could even redact block Foo entirely. Although that would be terrible from
         a code-organization point of view -->
</reference