For those of you who like their air on the oxygen rich side and have dedicated cylinders for this purpose, new standards for valves on cylinders come into force next year for cylinders using 22% 02 and above. There will be a new type of fitting called the M26 valve thread fitting which is similar to a DIN but slightly bigger.
The UK's HSE have fought against this imposition from some eurocrat but alas have lost. This new standard will known as the BS EN144-2003. This system has been used in the rest of europe since 2003.
There is a petition against this which you can access online at http://petitions.pm.gov.uk/SCUBA-valves/#detail if you wish to fight against the euro nanny who feels that divers are not capable of knowing what gas is in their own cylinders.