Try looking through the following....
inc -> xhtml_validator -> _xhtml_dtd.inc.php

// DEFINITION of allowed XHTML code for COMMENTS (posted from the public blog pages)

Not sure about it but there is a lot of info there that can be tweaked

Thanks, I think that's exactly what I was looking for.

All that stuff used to be in conf/_formatting.php

Let us know if you fixed it and what you tweaked if you did :)

It is fixed, thanks.

It's the same fix applied to older versions just in a different file.

The bit to look for is:

$comments_allowed_tags += array
(
	'ins' => $C_E_Flow,
	'del' => $C_E_Flow,
	'a' => $C_E_a_content,  // Allowing this will call for a whole lot of comment spam!!!
	'span' => $C_E_Iinline,
	'bdo' => $C_E_Iinline,
	'br' => '',
	'em' => $C_E_Iinline,
	'strong' => $C_E_Iinline,
	'dfn' => $C_E_Iinline,
	'code' => $C_E_Iinline,
	'samp' => $C_E_Iinline,
	'kbd' => $C_E_Iinline,
	'var' => $C_E_Iinline,
	'cite' => $C_E_Iinline,
	'abbr' => $C_E_Iinline,
	'acronym' => $C_E_Iinline,
	'q' => $C_E_Iinline,
	'sub' => $C_E_Iinline,
	'sup' => $C_E_Iinline,
	'tt' => $C_E_Iinline,
	'i' => $C_E_Iinline,
	'b' => $C_E_Iinline,
	'big' => $C_E_Iinline,
	'small' => $C_E_Iinline,
);

To find this section just do a search in the file for "comment spam".

The line for 'a' is commented out by default. I've found it safe to ignore the warning about spam though, as long as I have the catpcha plugin I get f**k all spam on my b2evo blog.

Thanks for that... might be of value to some others
Cheers