if there are no articles and no categories, code at sitemap() is not W3C valid. it is not a big issue (i guess there will always be some articles or categories), but let's make this piece of code completely perfect

in
sitemap()just find first line from snippet, and add red text
if (mysql_num_rows($cat_result) == 0) {
echo '<li><p>'.l('no_articles').'</p></li></ul>';
} else {
Hi
I don't see what you mean since my HTML sitemap page does validate with the original code.
More, you should not put a <p> inside an <ul>: it's not semantically correct for the document structure. The <li> tag is a list for items.