N3690 25.3.10 [alg.reverse]/2 says: "Requires: *first shall be swappable (17.6.3.2)."

This is inconsistent with the other algorithms, which require ValueSwappable from iterators instead of swappable from elements (e.g. see 25.3.13 [alg.partitions]/6 and many other places). These requirements are synonymous, so this is an editorial issue. The only exceptions in Clause 25 are swap_ranges() and iter_swap() which must require "swappable with" which is special.

I recommend changing 25.3.10 [alg.reverse]/2 to say: "Requires: BidirectionalIterator shall satisfy the requirements of ValueSwappable (17.6.3.2)."