Re: extended rx.el

[Richard Stallman]

    Currently both sregex.el and rx.el do regexps as sexps and there's a
    separate notation of Shivers' which they don't try to be compatible
    with.  These changes generalize rx.el in various ways and make it
    more-or-less compatible with sregex as far as I can tell and allow SRE
    forms where possible, which may provide a better chance of remembering
    the names.  The exception I know is that the `repeat' form is
    restricted relative to sregex.  Apart from that, I think you could use
    `rx' and `rx-to-string' as aliases for the corresponding sregex names.

It sounds like a good idea to simplify these two packages into one.
Could you explain more about how `repeat' is more restricted in rx?