> Give that property lists are as far as I can tell not defined at all
> in the current world of Scheme, shouldn't we start the SRFI process
> for them now so SRFI 198 has something to point at?

A property list is really just a "spread out" association list (alist).
The structure is so simple that it doesn't really need much supporting
infrastructure to be used effectively. For general usage a `plist-assoc`
would be nice, but for SRFI 198, `foreign-error-ref` would do its job.

More utilities would definitely be nice, but not really necessary when a
plist is just passed into `make-foreign-error` after which the
foreign-error abstraction takes care of everything behind the scenes. In
fact, the implementation can even convert the plist into an alist or a
hash-table internally.

> BTW, here's their definition from the Common List HyperSpec:
> http://www.lispworks.com/documentation/HyperSpec/Body/26_glo_p.htm#property_list

Good find. Indeed, plists have a long history in Lisp. Emacs uses them too.

Fun fact: any plist is built out of the same number of cons cells as the
equivalent alist.