"Outline" algorithm

I picked another page of the HTML spec at random to investigate the question

Next pick was across Secton 4.1.11.1 "Creating an outline"

which contains a lengthy description of an algorithm for computing
an "outline".  Now, is there any precedent, common practice, or
"cowpath" for outlines? Is there any reason why authors would care
exactly about the computation of the "outline"?

As far as I can tell, there are 41 occurrences of the word "outline"
in the spec, and the only reference to this algorithm is in section 4.8.1
on determining a caption for an image, which says:

# 3. Run the algorithm to create the outline (page 192) for the document.
# 4. If the img element did not end up associated with a heading in the outline, or if
#  there are any other images that are lacking an alt attribute and that are
#  associated with the same heading in the outline as the img element in question,
#  then there is no caption information; abort these steps.

which I can't tell if there is any reason why HTML should contain
such a thing, that it would correspond to common practice, or any
requirement listed in the "design principles".


If a browser wants to implement an "outline" algorithm, why would they
use this one?

So the whole section doesn't seem to make a lot of sense. A lot
of normative requirements for a complex implementation for computing
an outline with no applications?

Is this a remnant from something that was inserted and later removed?
What were the design principles for deciding which additions to add?

Larry
-- 
http://larry.masinter.net

Received on Tuesday, 26 May 2009 04:42:17 UTC