I did look on the net for an on-line link to the full tariff rules, but could not find one. The full rules should be available upon request from the carrier. You often see this referenced on tickets or at the check-in desk along the lines of "full conditions of carriage are available upon request from the airline ticket counter or corporate office" of something like that.

Perhaps someone can request this and post it somewhere??

My post above was prefixed by "My understanding is as follows". My information comes from someone involved heavily in the industry for many years who has proved to be very reliable and accurate in the past, who relayed an experience where he claimed payment for invol cancellation from QF for a PER-SYD business class flight under rule 90, and he noted how the QF station manager in PER was horrified at just how much cash he had to hand over.