RADIO is a TYPE attribute value to the INPUT element for FORMs. A radio
field represents a boolean choice. A set of radio fields with the same
name represents a one-of-many choice. At any time only one button of a
Radio button group can be ON, and only the selected radio item should be
submitted. If none of the radio buttons in a group are ever selected,
the name/value pair should not be submitted.
This is a method of giving access/focus to an active HTML element using
a keyboard character. This is a common GUI paradigm also known
as a "keyboard shortcut" or "keyboard accelerator"
A single character is used as the value of this attribute. In addition,
a platform-dependent key is usually used in combination with the
ACCESSKEY character to access the functionality of the active field.
[A single, case-insensitive character from a browser's character set.]
Deprecated in HTML 4.x/XHTML 1.0. Dropped in XHTML 1.1 in favor of CSS.
This attribute specifies the alignment of text following the INPUT
reference relative to the field on screen. LEFT and RIGHT specify
floating horizontal alignment of the form field in the browser window,
and subsequent text will wrap around the form field. The other options
specify vertical alignment of text relative to the form field on the
Values:Left | Right |
Top | Texttop |
Middle | Absmiddle |
Baseline | Bottom |
This is a required attribute that associates a symbolic name to the
field for submittal to the form processing script. A Radio button
that represents a portion of a Radio GROUP will have the same
NAME as the other Radio buttons in the group.
This is an SGML Document Access
(SDA) attribute. SDA attributes are designed to transform HTML (and
other SGML-based documents) to the ICADD
DTD - which is used in creating accessible documents for users with
visual disabilities (rendering in Braille, large print, speech
synthesis, etc.) The attribute value specifies content to be added
BEFORE the original element content (in this case the string
"Input: ") when the SDA document is rendered.
"Tabbing" is a method of giving access/focus to an active HTML
element using a standard keyboard sequence. All the active elements in a
document can be cycled through using this sequence (ex: Windows TAB key.)
The order of the active elements in this cycle is usually the order they
occur in the document, but the TABINDEX attribute allows a different order
to be established. The use of this attribute should create the following
tabbing order cycle if the browser supports the attribute:
Active elements using the TABINDEX attribute with positive integers are
navigated first. Low values are navigated first.
Active elements not specifying any TABINDEX attribute
Those elements carrying a DISABLED attribute or using negative TABINDEX
values do not participate in the tabbing cycle.
DTD Note: I listed READONLY as being supported in
HTML 4.x - it technically is...it is listed in the DTD for the
INPUT element, but the DTD comment (which is not legally enforceable) says
that the READONLY attribute should only apply to TYPE=TEXT or PASSWORD.
Netscape versions 2.0 and above have a small idiosyncrasy relating to
background images with this element. The background image of the
document (if one is specified) is not used inside a square region
surrounding the radio button. If the document has a background color,
it is used in the "non-radio" portion of this square instead. This does
not happen before Netscape 2.0 - it appears that form field rendering
was changed for version 2.0.
Relating to the last issue is a similar bug in Netscape 4.x. If a
BGCOLOR attribute is declared for a table - or a cell within a table -
the rendering boxes of any radio buttons (also checkboxes, and to a
very small extent - INPUT FILE fields) in that
cell/table will not use the indicated BGCOLOR - it will instead use
the BGCOLOR of the document itself. If you use Netscape 4.x, you will
see this bug apparent at almost every large-scale site you go to. Workaround: Using the CSS
[-->Index DOT Css] property on the
radio button element itself, set to the background color of the
cell/table that you are in, things will be correctly displayed.
Opera 2.1x has essentially the same check/radio-form-field-rendering-on-background-color
bug that Netscape does, but the conditions are less stringent. Opera
2.1x just doesn't seem to be able to render a specified background color
in the transparent areas of these rendering boxes. This is fixed in
Opera 5/6: Using the DISABLED attribute still sends the name/value pair
for the element to the form processing script. It should not do this.