[whatwg] Allowing authors to annotate their documents to explain things for readers

[Ian Hickson]

One of the use cases I collected from the e-mails sent in over the past 
few months was the following:

   USE CASE: Allow authors to annotate their documents to highlight the key
   parts, e.g. as when a student highlights parts of a printed page, but in a
   hypertext-aware fashion.

   SCENARIOS:
     * Fred writes a page about Napoleon. He can highlight the word Napoleon
       in a way that indicates to the reader that that is a person. Fred can
       also annotate the page to indicate that Napoleon and France are
       related concepts.

This use case isn't altogether clear, but if the target audience of the 
annotations is human readers (as opposed to machines and readers using 
automated processing tools), then it seems like this is already possible 
in a number of ways in HTML5.

The easiest way of addressing this is just to include text bringing the 
user's attention to relationships:

   <p>This page is about Napoleon. He was my uncle and lived in 
   France.</p>

Individual keywords can be highlighted with <b>:

   <p>This page is about <b>Napoleon</b>. He was my uncle and lived in 
   <b>France</b>.</p>

Prose annotations can be added to individual words or phrases using the 
title="" attribute:

   <p>This page is about <span title="A person">Napoleon</span>. He was my 
   uncle and lived in <span title="A hamlet near Drummond, in Idaho, 
   USA">France</span>.</p>

These typically show as tooltips.

To highlight material on the page that might be relevant to the user, e.g. 
if the user searched for the word "Uncle" and the site wanted to highlight 
the word "Uncle", the <mark> element can be used:

   <p>This page is about Napoleon. He was my <mark>uncle</mark> and lived 
   in France.</p>

The same element can be used by a reader editing an existing document to 
highlight the parts that warrant further study, possibly using the 
title="" attribute to include notes:

   <p>This page is about Napoleon. He was my uncle and <mark 
   title="really?">lived in France</mark>.</p>

Links can be used to link parts of a document together to indicate 
relationships:

   <p id="napoleon">My uncle was called Napoleon. See also: <a
   href="#france">France</a>, <a href="#uncle">Uncle</a>.</p>
   ...
   <p id="france">France is a hamlet near Drummond, ID. My uncle lived 
   there. See also: <a href="#napoleon">Napoleon</a>.</p>

In conclusion, this use case doesn't seem to need any new changes to the 
language.

A number of further use cases remain to be examined, including some more 
specifically looking at machine-readable annotations rather than 
annotations aimed directly at human readers. I will send further e-mail 
next week as I address them.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'