The University of Oklahoma has committed expensive human resources (yours and mine) to insure that all web pages on its servers are "accessible" to people with "disabilities". There is an internet "cop", or a so-called "Bobby" in the gentle English world, that can check to see if your web page is Bobby Compliant. My page it.metr.ou.edu/html/htmlex/ex1.html doesn't do very well. You can save yourself the effort of typing my URL into the tester by clicking this pre-typed link. Note the intimidating Bobby hats. Those Bobby hats appear because the images used for icons are referenced without an alt tag. For example, on my page I use:
<img src=im/l_red.gif >
The Bobby would prefer I use something like
<img src=im/l_red.gif alt="This little red ball is really only a two- dimensional image, so there is no need to panic" >
That way, when somebody points the mouse to the image, the browser will display the alt message and perhaps mitigate any potential phobias of small, spherical red objects.
But it is difficult for those of trained in meteorology to conceive of all the disablities that people may bring to our web pages. But rules are rules. Even though the gentle English Bobbies don't carry a pistol, I would rather not tangle with them. We can make the Bobbies go away by just adding a simple alt="pix" to our img tags. Apparently the Bobbies aren't too keen on vigorous enforcement. For them, as well as us, this may just be an excercise in CYA.
Nevertheless, some of us are taking this Bobby challenge more seriously than other, as you can see at weather.ou.edu. But a Bobby compliance check of that page still produces a lot of whining. One might have hoped, after all that effort, for the Bobby thing to say "Jolly good effort! You are making progress!". But, sadly, the Bobby thing is somewhat ill-mannered...
In order to expedite this little exercise in CYA, I have developed some perl and python scripts that use regular expression to go through .html files and add an alt="pix" where no alt tag is present. Scripts to reverse the operation are also available. Be careful with these scripts. You may want to experiment with them as in:
cp precious.html junk.html bobby.pl junk.html
If you are brave, you may try things like bobby.pl *.html. The following scripts are commented, and are best viewed with an editor that tags the syntax, like gvim. It is your choice to work with either .pl or .py, they both do the same thing.