I think also that the "C" may also refer to when the a/c does not contain business class seats or if so , they are not sold as such.I had award bookings from ASP to SYD in June-NO more .The aircraft has apparently been converted to one without J class.
ASP SYD 1315 1640 QF 791 JC DC Y9 H9 K9 M9 L7 S0 VC O0#733*C 5
Ozflier