Many thanks for the reply, the references are very useful.
So under EASA you would have listed (for example) in XII Ratings, certificates and privileges
A139 (SP)
A139 (MP)
IR (SPH)
IR (MPH)
And consequently, without the (MP) a pilot would not be permitted to operate that particular type in a multi-crew environment? And vice versa for (SP).
Is that correct?