The aircraft must meet the higher catogory before flight. Meaning rpt is over charter which is over Aireral work etc. you may drop down a cat if only you have an EO an mel or a pus. Then the M/R must be endorsed in part 2 or to what else you may be using stating what the aircraft may be flown as or when. Example aircraft ferry flight between 30/09/14 to 10/10/14 day Vfr only most direct route to XYZ. Min crew permitted only. IAW pus ABC. Or as per say auto pilot U/S. Aircraft must be flown with two crew IAW MEL blah blah. Only execption to this is a mercy mission at which the aircraft is grounded at the end of the flight and has to be released by casa.
In other words it's a can of worms