They operate to the exemption which is not CAO 48
The exemption has a flight deck duty limit, which is different to a flight time limit - I can't remember what it is - around 9 hrs I seem to recall.
Basically the exmption has no daily flight time limit, it has a flight deck duty limit and a duty limit.
The operator that assumes flight deck duty is block to block is taking liberties as I have yet to see a crew walk on to a flight deck immediately push a button and depart.