Goldenrivett, the information you provided is in the beginning of the thread.
My question is this:
Where does it say that the ceiling has to be reduced by 1200 ft when the ceiling is anyway given for single engine. As some posts here suggests, if the ceiling is reduced by 1200 feet because a single bleed is supplying two packs, I would like to know where it says that the ceiling reduces by 1200ft when a single bleed supplies two packs.