This is the legislative year assigned to a piece of legislation. It might be a calendar year like 2002 or a parliamentary session indicated by one or two regnal years. Because of the need to support regnal years, it is of type string.
For secondary legislation, this is always a calendar year. For primary legislation, things are more complicated.
From 1963 onwards, Acts of the UK Parliament (both local and general) are numbered sequentially within each calendar year, so 1963 and later Acts should just have a calendar year here.
Earlier Acts of the UK Parliament were numbered within the session of Parliament in which they were passed, with the sessions named by the regnal years they spanned. These are coded in the same way as is used by legislation.gov.uk. Examples:
- Eliz2/1-2 is 1 and 2 Eliz. 2
- Geo6and1Eliz2/15-16 is 15 and 16 Geo. 6 and 1 Eliz. 2
- Eliz1/13 is 13 Eliz. 1
Sometimes, legislation.gov.uk has Acts recorded by calendar year pre-1963. This is generally a mistake.