too long

But again get after w3 validator & did not start a character reference. (& probably should have been escaped as &.)

following my part of url anchor tag codings

<?php

$split_name = explode('and',strtolower($res_cat['cat_name']));

$split_catname = str_replace('','&nbsp;',$split_name[0]);

$category_name = str_replace('and','&amp;',$res_cat['cat_name']);

echo "<li><img src='".$res_cat['cat_icon']."' alt='b_icon'/>&nbsp;&nbsp;<a href='catsec.php?act=cat&amp;cat_id=".rtrim($split_catname).''.$res_cat['cat_id']."'>".$category_name."</a></li>";


?>

Example:

http://mydomainname.com/catsec.php?act=cat&cat_id=energy-41.

I am confused. Help me in advance. Thanks.

I check the html you post and below here you find a the replacement that is correct by the W3C

<!DOCTYPE html> 
<html> 
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Test</title>
</head>
<body>
<div id="item-sec-1">
<ul>
<li><img src='assets/images/b2b/energy.ico' alt='b_icon'/>&nbsp;&nbsp;<a href='catsec.php?act=cat&amp;cat_id=energy-41'>Energy &amp; Power</a></li>
<li><img src='assets/images/b2b/elec.ico' alt='b_icon'/>&nbsp;&nbsp;<a href='catsec.php?act=cat&amp;cat_id=electronics-42'>Electronics &amp; Electricals</a></li>
</ul>
</div>
</body>
</html>

The problem with your html is that there where -- in the code. And also you missed the title tag that must be there.

if you want to make a comment you should use <!-- comment here -->

I hope this helps you.