A set of checkboxes should be grouped together semantically by enclosing them within the fieldset element. The default visual effect of fieldset and legend elements can be modified in CSS by overriding the “border” property of the fieldset and the “position” property of the legend.
Engine scans forms containing multiple <input type=checkbox> elements with the same name attribute and not contained in a fieldset element
A set of related controls should be grouped together semantically to facilitate being treated as a single control, as well as to provide an additional group level description.