The Authoritative Handbook is the standard reference Handbook for the year in question. It contains the final version of course, major and minor structures for the given academic year, and is normally published on 1 November of the previous year.
Ancillary changes may take place after the Authoritative Handbook is generated (such as to unit offerings) and new courses may be offered; these will be reflected in the online Handbook (and thus appear in any print Handbook generated subsequently). Nonetheless, the Authoritative Handbook remains the reference point for the determination of matters relating to the degree regulations, academic progress, credit and exemptions etc.