Would you believe they prevent you selecting and copying the text of their licence in the PDF?! How anal is that?!

Anyhow…

"Creative Commons

These terms have been aligned to be interoperable with any Creative Commons Attribution 3.0 Licence. This means that you may mix the information with Creative Commons licensed content to create a derivative work that can be distributed under any Creative Commons Attribution 3.0 Licence."

http://www.ordnancesurvey.co.uk/oswebsite/opendata/licence/docs/licence.pdf

Appears they want it to look like this… http://creativecommons.org/licenses/by/3.0/ - I dunno what the abbreviation is supposed to be for this, perhaps someone will confirm?

Roger