html5: Significance of attribute named required in checkbox/radio

Question

On form submission, how could you possibly mark a checkbox/radiobutton as required?

Source of inspiration: Pekka\'s answer to a question

Answer 1

I tested required attribute for Radio Buttons today on Firefox 17.0.1 on XP SP2.

It seems to comply with the specification of required attribute for radio buttons/groups. As Firefox prompts "Please select one of these options." for both of the code snippets below:

Either you set required attribute for each of the radio buttons

Or Any One of the Radio elements

Any comments and updates are welcome.