Unusual .UK subdomains

I thought that all .uk net addresses were further scoped by an appropriate second-level domain, e.g. ".co.uk" for companies, ".ac.uk" for academic institutions, ".gov.uk" for governmenty-type stuff, but apparently not: I mis-typed my shortcut for Bloglines yesterday, and ended up at the British Library, which is just "bl.uk".

There are a few other anomalous British second-level domains floating around, such as "nls.uk" for the National Library of Scotland, and "nel.uk" for the National Engineering Laboratory. From this page at Nominet (the people who run the .uk top-level domain), it looks like they were created before the .uk structure was formalised.

That's your piece of trivia for the day.