Thanks very much to Chris and to Philip Bewig, the author of SRFI 41.  After discussing this change with them separately, I've decided to add a link to Chris's improvement to the Status section of SRFI 41.  (The reference implementation was included in the text of the SRFI, which was finalized years ago, and this change isn't a fix for an error, so I decided not to modify the reference implementation, even in the repo.  This link, though, should help implementers find this improvement.)