Why do people ask these questions here instead of knowing where this most basic of information is to be found?
It's very simple really....2 reasons.
1. Because the UK AIP is not my home AIP, nor the one concerning the airport in question. The Irish AIP has no such decode in it. (Thanks for pointing it out in the UK AIP...I'll keep it for future reference). Why would I look up the UK AIP for the answer? The UK is not connected to my question in any shape or form.
2. Because most skills in life are of the sort that you use or you loose. In 6 years of flying, this is the first time I've had to decode such a thing. Even if I had learnt it during training (which I didn't...never came across it) it's unlikely I'd remember how at this stage. Most METARS don't include it, so there's little opportunity or need to learn and keep that skill current.
dp