RE: datatypes in Elisp Info: mention "things" for which there is no "thing" datatype - e.g. faces

[Drew Adams]

    > Finally, I'm ignorant: Just why is `face' not treated similarly to
    > `function' - why isn't `face' a datatype? If the answer
    > expresses a general
    > rule, then perhaps that rule should also  be included in the
    > doc, to clarify things.

    I tend to think of datatypes in lisp as being...

Whatever people decide on this should be reflected in the Elisp manual (i.e.
it should be updated). Currently, I'm not sure that your POV is reflected
there. There are two places where the `function' datatype is discussed,
which are linked: 1) Lisp Data Types and 2) Functions, linked through
`functionp' at Type Predicates. It's not clear whether the entire discussion
at Functions applies to the `function' datatype.

In general, perhaps we should be clearer when we are speaking of an
"official" datatype and when we are speaking rather more loosely.

If Elisp "datatype" does not reflect something objective and operational
(e.g. determinable by program), then perhaps we shouldn't speak of
"datatype" at all. IOW, perhaps we should either make it clear what
constitutes an Elisp datatype, and which "kinds of things" are datatypes, or
not speak of Elisp datatypes at all.