An <INPUT> element with `TYPE=RADIO' represents a boolean choice. A set of such elements with the same name represents a 1-of-many choice field. The NAME and VALUE attributes are required as for check boxes. Optional attributes are:
At all times, exactly one of the radio buttons in a set is checked. If none of the <INPUT> elements of a set of radio buttons specifies `CHECKED', then the user agent must check the first radio button of the set initially.
For example:
<p>Which is your favorite? <input type=radio name=flavor value=vanilla>Vanilla<br> <input type=radio name=flavor value=strawberry>Strawberry<br> <input type=radio name=flavor value=chocolate>Chocolate<br>