Hi I have developed an XML file to show the structure of my website in OPML.

Each page is an 'outline' element and if that page has a subpage it is a 'nested outline' element. From this my XSL creates breadcrumb, sibling, child navigation, title, meta-data, and sitemap and A-Z HTML pages.

An extract from the file is

<?xml version="1.0" encoding="UTF-8"?>
<opml version="1.0">
	<dateCreated>Tues, 4 Nov 2008 16:00:00 GMT</dateCreated>
	<dateModified>Tues, 4 Nov 2008 16:00:00 GMT</dateModified>

<!-- root home page -->	
<outline text="Home" category="home"  description="description for home page" type="rss" url="index.php" xmlUrl="http://www.example.com/structure.xml" htmlUrl="http://www.example.com/index.php">

  <!-- primary gallery -->
  <outline xmlUrl="http://www.example.com/structure.xml" text="About this site" category="primary-gallery"  description="description for about this site" type="rss" url="about-this-site.php" htmlUrl="http://www.example.com/about-this-site.php">
    <!-- secondary gallery -->
	<outline xmlUrl=http://www.example.com/structure.xml" text="Customise" category="secondary-gallery" description="description for Customise" type="rss" url="customise.php" htmlUrl="http://www.example.com/customise.php"></outline>
However I want to use other attributes which are not covered by OPML like keywords (so I can reuse this data in the webpages).

Is the OPML file I have created useful for search engines, rss readers? (I have a separate RSS file, I had to use the type 'rss' because 'link' doesn't allow nested elements).

Should I just use my own custom XML tags for this document and output a sitemap.xml file?

Any advice would be appreciated.