The AIP is quite explicit about the IMC minima. Para 3.3.2 in section AD 1.1.2 states 'Pilots with a valid IMC/Instrument Weather Rating are recommended to add 200 ft to the Instrument Rated pilots' DH/MDH, but with absolute minima of 500 ft for a precision approach and 600 ft for a non precision approach' I would read that to mean that the 500 and 600 ft figures are not just recommendations but requirements.
absolute according to the COED means
1. complete, perfect
2. pure
3. unrestricted, independent
4. not in usual grammatical relation !
5. not relative or comparative
I cannot find a meaning 'mandatory' or 'not just recommended'.
absolute here means 'not relative to the IR pilot DH/MDH'. It is still a recommmendation.