gecko-dev/mail/base/content/contents.rdf

<?xml version="1.0"?>

<RDF:RDF xmlns:RDF="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
         xmlns:chrome="http://www.mozilla.org/rdf/chrome#">

  <!-- list all the packages being supplied by this jar -->
  <RDF:Seq about="urn:mozilla:package:root">
    <RDF:li resource="urn:mozilla:package:messenger"/>
  </RDF:Seq>

  <!-- package information -->
  <RDF:Description about="urn:mozilla:package:messenger"
        chrome:displayName="Messenger"
        chrome:author="mozilla.org"
        chrome:name="messenger"
#expand chrome:localeVersion="__MOZILLA_LOCALE_VERSION__"
#expand chrome:skinVersion="__MOZILLA_SKIN_VERSION__">
  </RDF:Description>

  <!-- overlay information -->
  <RDF:Seq about="urn:mozilla:overlays">
    <RDF:li resource="chrome://messenger/content/messenger.xul"/>
    <RDF:li resource="chrome://messenger/content/addressbook/abSelectAddressesDialog.xul"/>
  </RDF:Seq>

  <!-- messenger items for Messenger -->
  <RDF:Seq about="chrome://messenger/content/messenger.xul">
    <RDF:li>chrome://messenger/content/mailMessengerOverlay.xul</RDF:li>
  </RDF:Seq>
  
  <!-- messenger items for Select Addresses dialog -->
  <RDF:Seq about="chrome://messenger/content/addressbook/abSelectAddressesDialog.xul">
    <RDF:li>chrome://messenger/content/mailOverlay.xul</RDF:li>
  </RDF:Seq>
  
</RDF:RDF>