In Gemany sleeving is rare, PE is either g/y or red (before 1971) We may not use any other wire. In case of non-existance you're supposed to add a separate, paralleled PE cable.
The only accepted and mandatory(?) sleeving is blue on a g/y wire to mark a PEN. Blue PENs with g/y sleeving are not accepted either.
Interesting to see that I wire the same way what we call "wire saving 2way switching": brown = L, black = traveller (here "communicator"), gray for the lamp. But there is absolutely no rule here, except for this one: "Everything but g/y can be live".
