basic_filebuf::sync(): Is this a mistake on cppreference.com?

Question

The page for std::basic_filebuf::sync() says that

sync() or its equivalent is implicitly called by ... seekoff(), and seekpos() ...

But I cannot seem to find any mention of this in the language spec, neither here or here.

My read of the filebuf portion of the spec for both seekoff() and seekpos() is that it isn't even clear that they effectively accomplish what sync() does (among the other things they're to do), let alone call it or its equivalent.

Is this phrasing on cppreference a misleading piece of information?