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Visible, simple, accessible sites

From: John Nissen <jn@tommy.demon.co.uk>
Date: Fri, 17 Sep 1999 17:04:51 GMT
Message-Id: <53732@tommy.demon.co.uk>
To: wai@tommy.demon.co.uk
Hello Judy and WAI friends,

Here a list of points arising from consideration of web
usability for elderly people, as part of the Senior Online
project (part funded by the EU).  I have divided them into
points about visibility, simplicity and accessibility.

1. Visibility

First of all some points on visibility for sighted people:

1.1  Have largish text but not too large.
Probably 12 or 14 point is around the optimum size.  If too large,
there may be too much scrolling for comfort.

1.2  Have sensible contrast
Avoid very dark backgrounds on which the cursor may disappear,
and avoid dark text on dark background or light text on a light
background.  (I have come across sites with purple text on navy
blue background, where I couldn't read a word.)

1.3  Avoid italics - leave browser to choose emphasis
Small italic characters do indeed look wobbly!  Also use of explicit
italics in HTML clashes with browser use of italics to highlight links.  

1.4  Don't have anything blinking
This is irritating, distracting, and potentially harmful for people
with a certain type of epilepsy perhaps.  (Does this type continue
to old age?)

1.5  Don't have important information just off bottom of page.
I've been caught out myself, when I thought there was a full page
on the screen, but I need to scroll down to see a vital link at the
bottom of the page.

1.6  Delimit link text clearly 
Separate links clearly, and try to keep link text on one line.

2. Simplicity

Then there are some points about keeping it simple for the user:

2.1  Don't provide a top button (to take user to top of page)
This is confusing to the user.  The user has to learn to
scroll anyway, and it's not hard to get to the top.  If they use
the button rather than scrolling, then Back takes them to the
bottom again.  I find that irritating, but I suspect it will be
a source of confusion for most elderly people.

2.2  Don't have back and home buttons on the page
Again these are confusing, as the behaviour conflicts with that
of Back and Home buttons on the browser.

2.3  Have a hierarchy, navigated top-down
Keep the site hierarchical, and encourage people to enter at top level
(by premoting the URL for the top level page, by always refering to the
site by this URL, by using it as link from other sites, etc.).
Have links only down the hierarchy, except for cross-links where 
they are natural (e.g. in an index, see 2.4).

2.4  Have a guide to site
Have a list of contents, site map, site search, and/or index to the site.
Such a page can help a user considerably in finding things on the site.
To keep with hierarchy principle, this page should be at or immediately
below the top level.  The information to which this page refers should
be at lower levels.  (The May 1999 WAI content guide violates this rule!)

2.5  Avoid next/previous buttons - large pages are OK
The links from a higher level (e.g. table of contents) may point to 
different named "anchor" points in single large page at the lower level.  
Search results should be on single page.  (Most if not all modern browsers 
can start displaying the initial results while the rest of the page continues
to be downloaded.)

2.5  Keep to a few consistent heading levels
Keep to three levels at most (i.e. section, subsection and subsubsection), 
each with consistent H tag numbering.  If you are tempted to have more,
have another level in the site hierarchy instead.

3.  Accessibility

Then there are aspects relevant when the user has assistive technology
(AT) such as a special browser or a screen reader used with conventional

3.1  Tables.  
These are OK if the tags can be ignored by AT without changing
the meaning and essential order of presentation of the information.
Thus if you have a row of buttons and then a row of labels on those
buttons, there is a problem.  But if you have a row of cells each
containing a button and a label, that may be OK.

3.2  Frames.  
Some AT doesn't support them, or support them well.  But I'm against 
them anyway.  This is mainly because I believe frames are unnecessary.
In general I believe that it is best to leave the navigation
commands to the browser - with Back and Forward, and to structure
the site in a hierarchical fashion.  The user can be confused in
a frame if they try using the Back button.  I know this, because I
have got confused myself!

An exception may be for a "help" frame, where context-sensitive
help can be given alongside the page where the user is having
difficulty.  However it is not obvious how AT should deal with
such a frame.

3.3  Pictures
These need to have have alt text, or other form of descriptive
text with them.

3.4  Java for snazzy presentation
In general it is impossible for AT to support Java applets and
be able to transform the information, generated by applets for display
on the screen, into an alternative non-visual medium.  However Alt text 
can be used to provide the information, as for pictures.
3.5  Javascripts
In general it is impossible for AT to support client-side scripts.  
However if one can ignore them, and still have access to necessary 
information from plain text, then that's OK.


Access the word, access the world       Tel/fax +44 181 742 3170/8715
John Nissen                             Email to jn@tommy.demon.co.uk
Cloudworld Ltd., Chiswick, London, UK   http://www.tommy.demon.co.uk
Received on Friday, 17 September 1999 14:11:41 UTC

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