Yes, very simple.
P1 = the person appointed by the operator to be the pilot in command. He doesn't need to touch the controls for the whole flight, he is still the P1 and has final authority as to the disposition of the aircraft at all times.
P1U/S is a co-pilot who has been appointed by the operator to act as a PIC under the supervision of the P1 who has been appointed by the operator in that supervisory role. The P1U/S does not have final authority as to the disposition of the aircraft. Ordinarily a P1U/S log book entry should be certified (i.e. signed off) by the P1 who supervised the P1U/S.
Last edited by gulliBell; 20th Aug 2016 at 23:09.