Originally Posted by pbd456

my theory is that airlines can do anything they like. i personally would not touch the ticket until first segment is flown. but the fare rule says clearly that it is okay to change date except for first flight (i believe) but airlines prefer to reissue tickets whenever the PNR is changed to keep eticket in sync with PNR or PNR will be cancelled. since airlines will reissue, they will look at the current fare for repricing if it is unflown.