I applied to Infolinks in order to experiment with them on my sites. My application was denied because of 'incompatible tags'. After having written to support, I received the following reply:
The <fieldset> tag is used to group related elements in a form (draws a box around the related elements). The Infolinks algorithm systematically ignores the contents of the <fieldset> tag to avoid placing highlighted links in forms.
Well, I have dozens of fieldsets in my sites, and none of them are in forms. Are fieldsets supposed to be ONLY in forms?