A revised edition is issued every year on or close to 1st April. The update incorporated in the revised edition enactments will be brought into force from 2nd January in the previous year to 1st January in the current year (inclusive).
New laws and amendments coming into force between 2nd January and 31st March in a given year will not appear in that year's revision, but in the following year. Nor will they be indexed (i.e. shown in the previous year's revised edition) until after the new revised edition goes live.