Re: LYNX-DEV radio buttons

[Al Gilman]

  From: "Herschel P. Goldstein" <address@hidden>
  To: address@hidden
  Subject: LYNX-DEV radio buttons
  
  I run the web site for the neuroscience course here at Thomas Jefferson
  University. At the site I provide a quiz service where students choose the
  best answer for a multiple choice question by selecting a radio button. In
  the past and on all the graphical browsers all buttons within a name group
  are unselected unless a checked modifier is provided. With lynx 2.7 the
  first choice in each name group is selected by default. Is this a problem
  and how do I fix it if it is? 

If you want "none of the above" to be a legal answer, and you want
your form submitters to be able to use Lynx, you should include that
as (probably the last) radio button and mark it CHECKED in the source 
page.

The language from the HTML 3.2 spec follows:
-----------------------------------------------------------------------------
                                  HTML 3.2 Reference Specification (p61 of 131
        type=radio
                Used for attributes which can take a single value from a
                set of alternatives. Each radio button field in the group
                should be given the same [93]name. Radio buttons require
                an explicit [94]value attribute. Only the checked radio
                button in the group generates a name/value pair in the
                submitted data. One radio button in each group should be
                initially checked using the [95]checked attribute.
----------------------------------------------------------------------------

While it uses the squishy "should" instead of real specification
language, this does encourage the Lynx behavior.  Lynx treats a
radio button widget as requiring the selection of one and only one
of the INPUT tags which share the type RADIO and a common NAME.

By a radio button widget I mean the a set of all INPUT elements
of type RADIO appearing in one FORM and sharing a common NAME.

For Lynx, <none> is not a legal state for such a widget and
_some_ name-value pair will _always_ be included for any NAME
appearing in an INPUT/RADIO in that FORM when the FORM is
SUBMITted.

Lynx treats a FORM received which contains a radio button widget
with no button CHECKED as erroneous, and CHECKs the first-listed
element as a matter of error recovery (bring radio buttion into
conformance with its type).

Clearly other browser behave otherwise, and treat the widget as
null-bearing.  The disadvantage with that sort of behavior is
that an individual radio button cluster cannot be reset to its
rest state without resetting the whole form.  Or else there would
have to be an UNSET action for radio button subelements which
left the array in an all-clear state.  

It is unlikely that you are going to get either Lynx or
OtherBrowser to change behavior any time soon, so I suggest that
you heed the "should" admonishment in the 3.2 document and insert
an explicit "none of the above" choice whenever you want the
possibility of a NULL answer for a radio button or SELECT
element.

--
Al Gilman

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