Re: User-reserved element in byte code vectors

[Richard Stallman]

    On the other hand, I'm not sure it's really better than omitting the slot
    now, and later adding a `super-curry' funvec-kind that has the slot -- code
    that cares about funvec layout would have to be amended to deal with non-nil
    values of the slot anyay, so making it understand `super-curry' isn't much
    different, right?

If we add this feature, such funvec objects will probably get written
into files, or otherwise saved.  It would be better to avoid
changing the format incompatibly.