When the user clicks on thebutton of a form, name/value pairs are sent to the handler script for each successful control.
Here are the rules that define when a control is considered successful.
If a control is disabled, it cannot be successful.
Checkboxes that are set (on) are successful. Unset (off) checkboxes are not successful.
For a group of radiobuttons that have the same control name, only the one that is currently set is successful.
If you don't specify which of the radiobuttons in a
group is initially set by default (with
checked='checked'), the result is
undefined. When you create a form with radiobuttons,
always designate a default radiobutton.
select element, only the choice
that is selected is considered successful.