"hidden" explanations

One of the major shortcomings of our work is that we are (mostly?) all 
still hung up on printed stuff.

THIS IS THE WEB - HTML AND ALL THAT!

Our document need not be like something to be printed out in order to read 
it in the comfort of one's favorite chair. There is a feature on many pages 
in which one lands on a particular item and a box of explanatory 
(contextual help) text shows up. If you read:

2.5 Ensure that the logical structure of the content is preserved in the 
markup or data model, together with any additional semantic
distinctions that facilitate rendering of the content in the visual, 
auditory and tactile modalities.

and then push some key and have superimposed on it enclosed in a box:

The logical structure of the content needs to be explicitly
preserved for two purposes. First, it allows style rules (other
than those provided by the author) to be applied, thus enabling
the content to be presented effectively and appropriately in
different modalities, with a range of output devices. Secondly,
it provides the basis for structural navigation by the user. In
order for the content to be rendered in all three modalities,
it is also necessary to capture such distinctions as emphasis
and changes in the natural language or notation in which the
text is written. Note also that if this guideline is followed,
it will enable more sophisticated analysis of the content by
search engines and other document processing applications.

you have: 1) saved "real estate" on the screen making for a less daunting 
reading/viewing/listening experience; 2) saved cognitive loading; 3) 
avoided a "duh" for those who know what was meant in the first place. It 
would help both those who see the first rendering and would say "I knew 
that" when forced to wade through the explanation part and those who "click 
it up" and say "Oh! now I understand what that means."

We aren't making full use of the medium. It doesn't have to be presented as 
a whole. It doesn't have to be printed out. It should serve as an exemplar 
of what hypertext medium is all about. Inline links are so underused as to 
make one wonder if we really believe in this stuff.

--
Love.
                 ACCESSIBILITY IS RIGHT - NOT PRIVILEGE