Referring back to the online version of the UK Highway Code where I found this, the beginning states
The Highway Code
The road user and the law
Road traffic law
The following list can be found abbreviated throughout the Code. It is not intended to be a comprehensive guide, but a guide to some of the important points of law. For the precise wording of the law, please refer to the various Acts and Regulations (as amended) indicated in the Code.
and then there is a whole list explaining the abbreviations quoted under each section. It's here.
http://www.direct.gov.uk/en/TravelAn...code/DG_069869
That piece I quoted before comes from these laws, apparently.
[Laws CUR reg 98, 105 & 107, RVLR reg 27 & RTA 1988 sect 42]
http://www.direct.gov.uk/en/TravelAn...code/DG_069860