Repeat of proposed addition to Age calculations (pre-04 13.2.3)

I repeat my earlier request to add text to the age calculations
section. This text would allow cache implementers to improve on the
age correction algorithm that is now in that section.  The current age
correction algorithm does not always work and sometimes leads to an
avoidable loss of efficiency.  I feel that some implementers of caches
calling themselves 1.1 _will_ implement an improved algorithms whether
1.1 allows it or not.

Reference to the proposed text:

 http://www-uk.hpl.hp.com/people/ange/archives/http-wg-archive/1197.html

Koen.