Ah yes, the good old adaptor for using class 0 appliances in rooms with Schuko sockets! They never conformed to any regs because Schuko was purposely designed to prevent the use of class 0 plugs but they were incredibly common back in the day! Germany banned essentially all one-piece multi-way adaptors in 1959, mainly claiming that Schuko sockets couldn't take the mechanical strain of more than one plug. They remained legal in Austria, which was by then moving away from the German VDE regs, introducing the first edition of the new OVE regs in 1962, but I don't know for how long. You can still find them on many flea markets but I rarely see them used any more.
Travel adaptors are very hard to govern as they're often not sold in the country they're to be used in. I try to avoid them completely and have a large collection of home-built adaptors consisting of a local earthed plug, 1 m of flex at least 1 mm2 and a Schuko trailing socket. They're not perfect either though, those with 10 A plugs could be overloaded, at least in theory. In practice, I doubt anyone would carry around a load exceeding 10 A while travelling. I do wish my NEMA 5-15 adaptor had more than 18 AWG! A 18 AWG IEC lead was all I had available though. I didn't even realise that until I cut and stripped it, the outside diametre is roughly equal to H05VV-F 2.5 or at least 1.5!
