...my understanding is that LSALT is above the max. altitude the engines are certified to be relit. Last time I think I went over Afghanistan, LSALT just a bit lower.
As I understand the rules, supplementary oxygen is required on routes where terrain would prevent immediate descent to 10,000 feet in the event of depressurisation and the aircraft would need to remain above this altitude for some time during the diversion - e.g. some parts of Iran which would be on a direct Singapore - Europe non-stop flight.
Now, if the oxygen system is responsible for a depressurisation, where do we stand as regards a diverting aircraft flying above 10,000 feet for an extended time with insufficient oxygen to supply the passengers for the duration?
I hope the full implications of an unprecedented, unexplained and unexplainable aircraft oxygen system bottle explosion are becoming clear.