[rand.req.eng][rand.req.dist] What is `fmtflags`?

[frederick-vs-ja]

In [rand.req.eng] and [rand.req.dist], we seemingly treat fmtflags as an exposition-only data member of stream objects, but currently there's no such exposition-only member.

I guess we should say is.flags() and os.flags() instead. Can we fix this editorially?