AIP specification repeats Preservation Metadata requirements

[stephenmackey]

The AIP specification (p16 onward) repeats requirements detailed in the CITS Preservation Metadata and gives them unique 'AIP' requirement numbers. This is problematic for comprehension and for maintenance. In addition it introduces a different level term in 'COULD' as opposed to 'SHOULD' used in CITS Premis. I am not entirely sure of the definition of 'COULD' versus 'SHOULD' or 'MAY' but it would seem to demote the level from the one used in CITS Premis.