[css4-page] Cross-references

Context:
http://krijnhoetmer.nl/irc-logs/css/20130205#l-670

Daniel, in Tucson you talked about more powerful page headers/footers, 
bookmarks, footnotes, etc. Another feature that has a big demand for 
printing is cross-references. These allow, among other things, tables of 
contents with automatic page numbers.

GCPM adds a few functions for the content property, but these are 
under-specified and need some more spec work:

http://dev.w3.org/csswg/css3-gcpm/#cross-references

A table of contents would have internal hyperlinks in markup and page 
numbers added eg. with an ::after pseudo-element. Later we could imagine 
the whole TOC being generated in CSS, but let’s take one step at a time :)

Just keep this is mind for now. I’m happy to discuss further when you 
get to css4-page ideas.

Cheers,
-- 
Simon Sapin