A form-associated element can have a relationship
form element, which is called the element's
form owner. If a form-associated element is
not associated with a
form element, its form
owner is said to be null.
A form-associated element is, by default, associated
with its ancestor
form element, but may have a
form attribute specified to
This feature allows authors to work around the lack
of support for nested
If a form-associated element has a
form attribute specified, then that
attribute's value must be the ID of a
form element in
the element's owner
Returns the element's form owner.
Returns null if there isn't one.