FYI

While looking at the fare rules for the DONEW4 fare ex-Australia on www.travel.com.au
, I found the following:

IF FIRST/BUSINESS CLASS IS N O T AVAILABLE ON A
FLIGHT - PASSENGERS WILL TRAVEL IN THE NEXT LOWEST
CLASS WITHOUT COMPENSATION - EXCEPTION: FOR
SERVICES WITHIN/BETWEEN THE USA AND CANADA WHERE
N O BUSINESS CLASS IS OFFERED BUSINESS CLASS
PASSENGERS MAY BOOK AND TRAVEL IN FIRST CLASS
SUBJECT TO AVAILABILITY(CONDITIONS APPLY).

(you have to scroll down and read the section titled "Notes" section in detail to find this)

Most people only see the part the says:

BUSINESS: D (QF/BA/AA/CX/IB/DI/AY*/EI*/LA*/LP*);
FIRST: A (QF/BA/AA/CX/AY*/EI*/IB/LA*/LP*);
*ECONOMY: Y (EI - DOMESTIC IRELAND FLTS);
*ECONOMY: Y (LA - DOMESTIC CHILE FLTS);
*ECONOMY: Y (LP - DOMESTIC PERU FLTS);
*ECONOMY: Y (AY - DOMESTIC FINLAND FLTS);
NOTES -
A)WHEN THE CLASS OF SERVICE FOR THE FARE PURCHASED
IS NOT OFFERED - BOOK THE NEXT LOWER CLASS OF
SERVICE USING THE ABOVE BOOKING CLASSES;
B)CAPACITY LIMITATIONS MAY APPLY ON THIS FARE.

(under the section titled: Class)