It is effecitvely an operator's issue and the relevant oversight agency's. Oh, not to forget, once the inevitable hits the fan, all of the sudden the commander is the responsible party.
Very little to do with manufacturers, in fact, I don't think Boeing pilot books mention it at all.
The relevant guidelines are to be found in the OPS regulations, dunno which one do you use.
The European JAR-OPS1 boils down to this: if you have a limitied pax O2 supply, you need to be at 14000 ft cabin press alt before it runs out. Once depleted, you have 30 mins to get to 10000ft.
Both apply at the same time, i.e. once the masks are deployed, it is
the time to 14k ft and
the time + 30' to 10k ft. (A/C certified above FL250)
Fly safe,
FD.
Silly me, the most important part left out:
If you cannot make the times, speeds, profiles and mountains move to fit, you are not eligible to fly there!