Re: spaces and alt-text. proposal for the ERT.

At 01:02 PM 12/7/99 , Charles McCathieNevile wrote:
>Suggestions / questions:
>
>2. If the image is the entire content of a link, and there is not another
>link in the document to the same target, harass the author.

see proposed changes, below.


>3a. Is   a unicode character for space?

for nbsp

>3b. THere is no defined handling for alt=" ", so it might no have the desired
>effect

using "" versus " " has been argued back and forth.  It is my 
interpretation of sifting through the archives that if the "desired effect" 
is a space between two characters, using an image for this is 
inappropriate.  We suggest style sheets.

Also, some people have favored "" while others like " ".  Most of the 
arguments have been based on the current state of the art handling of 
spaces.  However, it appears that "" and " " are currently handled the same 
[http://www.w3.org/WAI/GL/tests/spaces.html].  I was the only one to 
respond to the tests, so it only includes the 3 browsers I was able to test.

Many people pointed to the HTML4 spec where it says that "leading or 
trailing spaces" may be ignored.  However, is a single space trailing or 
leading?

    is inappropriate since it is intended to be used as a typesetting 
hint as Nir described on 17 November: 
http://lists.w3.org/Archives/Public/w3c-wai-gl/1999OctDec/0070.html
Alan Flavell also makes a good point about nbsp not being considered "white 
space" http://lists.w3.org/Archives/Public/w3c-wai-gl/1999OctDec/0069.html

Therefore, I don't think it matters much if we suggest that people use "" 
or " ".  Personally, it seems to be a matter of author preference.  Neither 
one is going to cause horrible things to happen (although "" has 
historically - i.e. it supposedly used to be ignored by Lynx but doesn't 
seem to be anymore).

If we look at the long term, I would suggest using a space since spaces are 
supposed to be preserved in XML.  However, I also agree that it is a matter 
of separating content from presentation.  A space seems to say, "there is 
formatting going on here" while null says, "it's decorative."

Again, I think it boils down to author preference.

>3d. If the image is decorative, use alt="" but ask if the author would like
>to associate a longdesc
I think it is up to the author, thus why I left it as either a blank or a 
short description.  It is my understanding that some users appreciate 
knowing what is on the page. If the author wants to support short 
descriptions for them, it is their choice.

As we look forwards to tools that will allow users to navigate the 
structure of a page, if a user chooses to navigate past images then we 
won't have to worry as much about users wading through alt-text that they 
don't care about.

Therefore, I once again include a proposal for review:
<proposal>
1. Flag images with:
* the IMG attribute alt="", alt=" ", and alt="&nbsp;" (or alt="&#160;")
* OBJECT (of type="image/gif" or "image/png" etc.) that has no text content.
(Note that OBJECTs of other types should be handled elsewhere in the ERT 
document.)

2. If the image is part of a link that has text (e.g., <a 
href="home.html"><img src="button.gif" alt=" ">Refer to our home page</a>) 
this is o.k.

2a. if the link does not have text, look for other links on the same page 
that point to the same URI and use the text from those.

2b. If no other links to the URI are found on the page, prompt the author 
for text to be included as a text equivalent of the image (or if the author 
wants to add it as text of the link.)

3. If the image is not part of a link, query the author for the use of the 
image.

3a. If the author identifies the image as a space between words and those 
words should not be separated, advise them to use &nbsp; (or alt="&#160;") 
instead of an image.

3b. If the image is a space that is used to format the layout of text, 
advise them to use style sheets, IMG alt=" ", alt="", or spaces in the 
content of OBJECT.

3c. If the author indicates the image has a function, advise the author to 
provide a functional text equivalent and if necessary a longer description.

3d. If the image is purely decorative and has no meaning to the content of 
the page, advise them to provide either brief descriptive text, or that 
they handle it as a "space" (see 3b), and suggest that they may also want 
to provide a longer description of the image (on IMG with the "longdesc" 
attribute or as text in the content of OBJECT).

Exceptions to this rule are image effects that could be created with style 
sheets, such as graphical list bullets. Advise authors to use style sheets. 
(See examples in the WCAG 1.0 Techniques document).
</proposal>

--wendy

--
wendy a chisholm
world wide web consortium
web accessibility initiative
madison, wi usa
tel: +1 608 663 6346
/--

Received on Tuesday, 7 December 1999 18:06:23 UTC