The OMA Ch 7 has changed a number of times - tweaked, here an there. I would have to agree with MM, it is clearly defined. The only issue is whether you want to fight over it or not.
One interesting change that not many seem to have noticed is the that to be acclimatized you now need an uninterrupted nights sleep. Previously you could fly a night turn, return to Dubai and still be acclimatized! So you could be sent off on a ULR later based on being acclimatized.
Now you require the nights sleep. Rostering response has been to roster a ULR followed by 2 days off (used to be 3) then roster a NIGHT turn, since you are unacclimatized and have a LONGER duty day!!! Makes no sense biologically but it's 'legal' Take a look at the 777 rosters and 90% are rostered with that night turn after a ULR.
There is no concern for what is healthy or safe.