Inoxydable also means rust-resisting. There is no stainless steel in or on that frame.
Peugeot used a very tough clearcoat over their chrome which gives it protection from rust. I don't know what it is, but I can say from experience that it's difficult to remove, even with paint stripper.
I just looked and my PA10 does have the tag on the bottom bracket shell, so the tag obviously doesn't prove it's a PX10.