Re: diff-mode documentation

[Richard Stallman]

    +    ("\C-ca" . diff-ediff-patch)
    +    ("\C-cr" . diff-reverse-direction)
    +    ("\C-cu" . diff-context->unified)
    +    ("\C-cc" . diff-unified->context)

Those key sequences are reserved for users (see the Tips appendix
in the Lisp Manual).  You need to use key sequences in the space
reserved for major modes (since Diff mode is a major mode).

    +    ("\C-c\C-k" . diff-file-kill)

That is ok.