SPIC is used under intergrated training to allow students to build PIC time.
It has no place in the logbook of someone who hasn't completed an intergrated course.
PICUS is multi crew or test and the examiner or Captain signs it
PIC is you sign the tech log and Captain the aircraft.
Dual when someone else signs the techlog who has a instructor rating and the purpose of the flight is instruction
Any other theorys on club checkouts etc are rubbish (pish
)
But I really can't get excited over it for a PPL, it only ever matters when applying for CPL/ATPL and in the event of an accident an insurance company having stipulations.
Its actually quite funny seeing some peoples log books that are hungry for PIC time. They try so hard to log it but they just end up looking like incompetent arses. Yet others don't seem to care one bit and log everything as dual. To be honest there is a strong link between taking the piss with PICUS etc and flying competence. If you spot PICUS entrys before a check ride/hour with an instructor its more than likey the pilot will be talent limited.