The reference implementation given for "Chicken, PLT Scheme and
MzScheme" doesn't actually implement the SRFI function "Returns names
and values of all the environment variables as an a-list."

So I'd say that either implementation doesn't belong in the document, or
the SRFI function should be revised to permit compliant implementations
to behave like that implementation does.

--
http://www.neilvandyke.org/