The whole body of a fire extinguisher used to be colour coded. Now (since Jan 1997) all (new) fire extinguishers are RED, with no more than 5% of their surface area being colour coded (new standard is BSEN3). There don't appear to be any other rules about this (important) colour coded area, so you'll see some examples where the colour coding just looks like part of the maker's logo. Well done the EU; another major step forwards for public safety.
So, if you ever have the misfortune to need to use a fire extinguisher, read the label even more carefully than usual before doing anything with it.
Richard