IMAGE is a TYPE attribute value to the INPUT element for FORMs. It
specifies an image that can be clicked upon to pass information to the
processing script. In implementation, this form TYPE acts much like the
INPUT TYPE=SUBMIT field, but unlike the SUBMIT field, the coordinates of
the image that were activated are sent back to the server in addition
to the rest of the form data.
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 IMG
reference relative to the graphic on screen. 'Left' and 'Right'
specify floating horizontal alignment of the image in the browser
window, and subsequent text will wrap around the image. The other
options specify vertical alignment of text relative to the image
on the same line.
Values:Left | Right |
Top [DEFAULT] |
Middle | Absmiddle |
Baseline | Bottom |
This attribute explicitly specifies the height of the graphic in pixels.
It is mainly used to create custom image dimensions without physically
changing the image itself. It can also be used to speed up display of the
document being downloaded so it can pre-render the document with image
placeholders while the images download.
This is a stand-alone attribute which is used during form submittal to
identify the image as a region-sensitive map. When ISMAP is used in an IMG
element, it is used in combination with a hyperlink to give the location
of a server-side area definition file. In the context of forms, it is
unknown how the browser sends the coordinates - possibly also by embedding
the INPUT element in a hyperlink.
The server-side map file is a series of shape names with associated
coordinate values that list corresponding URLs to jump to when the
coordinates are activated.
This attribute specifies the URL of a low-resolution image to be
downloaded before a higher resolution image specified in the SRC
attribute. The reasoning is that a low-resolution image is smaller
in size than a higher resolution image and is thus faster to download.
After the lowres image has been downloaded, it is displayed until the
high resolution image is downloaded.
Either an absolute or relative URL. All URLs should be URL encoded where required.
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.
This attribute specifies the URL (usually internal to the document) of
the client-side image map specification to be used if the browser has
that capability. If the argument to USEMAP begins with a "#"
it is assumed to be in the same document as the INPUT TYPE=IMAGE element.
[An absolute URL, a relative URL or an internal anchor name. All URLs should
be URL encoded where required.]
This attribute explicitly specifies the width of the graphic in pixels.
It is mainly used to create custom image dimensions without having to
physically change the image itself. It can also be used to speed up
display of the document being downloaded so it can pre-render the
document with image placeholders while the images download.
DTD Note: Support for the NAME attribute was added
to HTML 4.01 and did not exist in the original HTML 4.0 DTDs.
All of the surveyed browsers ignore any VALUE attribute, if it is present.
When the image is activated, the form data is submitted along with
two extra name/value data items: the X- and Y-coordinates of the point
of activation on the image. Coordinates are sent in this format - Item 1 -
Value: [x-position] Item 2 -
Netscape uses a non-zero value for the BORDER attribute by default.
Setting the value to zero eliminates the border.
Mosaic honors the BORDER attribute, but treats it as a binary setting -
if present and set to a non-zero value, a thin, hyperlink color line is
drawn around the image.
Linefeed and Carriage Return handling ( and
respectively) for the ALT attribute:
- Internet Explorer: All literal/unencoded or
encoded CR/LFs are maintained and displayed as intended.
- Netscape: All unencoded or encoded CR/LFs are
collapsed to nothing in ALT display (not the normal method for
spacing-character collapsing - usually it would collapse to a
[Test]Notes on the BORDER attribute in Netscape: This
attribute has been supported since version 1.0, but some changes have
happened. It looks like the attribute was NOT supported in version 2.0
at all, but support returned in 3.0. In version 6.0, the default border
color for borders is black, not the document hyperlink color as is the
case in other Netscape versions.
Opera 3.5-3.6x has a problem laying out form fields on the same
line as INPUT IMAGE fields... fields on the same line BEFORE the image
are top aligned with the top of the image, and fields on the same line
AFTER the image are bottom aligned with the bottom of the image. This
behavior is fixed in Opera 4. (If the fields are RADIO or IMAGE, they
seem to be immune to this effect.)
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.
The ALT attribute is exposed in Netscape 7+ by invoking a context
menu on the image (PC: right clicking) and choosing "properties."