Ah, one of Scott’s plugins. I’ve got no problem flipping his stuff. ;)
You don’t mention what the “specific ‘rel=’ attribute” is, but if you just want to make a static change to all links, you only need slip it into the <a>
tag that appears in each of the preg_replace() lines. For example, you’ll find this in the first preg_replace():
'$1<a href=\"https://$2.$3$4\" title=\"https://$2.$3$4\"$new_win_txt>'
Just modify it like so:
'$1<a href=\"https://$2.$3$4\" rel=\"value\" title=\"https://$2.$3$4\"$new_win_txt>'
Change ‘value’ to the rel attribute value you want to use. Then do the same for the other two instances of preg_replace(), inserting the rel between the href and title attributes that already exist in them.
Take note of how the double-quote marks both in the addition of the rel and other attributes are escaped out. It’s a PHP thing which allows the use of quotes within similarly quoted string values (double in double, or single in single). So you want to insert:
rel=\"value\"
and not:
rel="value"