dalla RFC 1866
8.1.2.4. Radio Button: INPUT TYPE=RADIO
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:
CHECKED
indicates that the initial state is on.
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:
Which is your favorite?
<input type=radio name=flavor value=vanilla>Vanilla
<input type=radio name=flavor value=strawberry>Strawberry
<input type=radio name=flavor value=chocolate>Chocolate
Berners-Lee & Connolly Standards Track [Page 42]