I booked the first half of a reasonably comprehensive DONE4 six months ago. The start date is February 2024, commencing in Japan and travelling through North and South America, Europe then back to Sydney for 2 months, before spending October and November in Asia, finishing in NRT at the end of November. I have been checking Expertflyer for D seats on 24 November SGN-NRT but JAL and Malaysian are displaying no availability in D out of SGN at all - plenty of availability for everything else? Can anyone tell me what this means? Apologies if this info is already available in here somewhere - I seem to be woefully inefficient at doing searches....