Cannot edit .BAK file--rename file

    Files with the extension .BAK are considered to be backup files,
    with more up-to-date versions of the files assumed to exist. There-
    fore, .BAK files shouldn't ordinarily be edited.

    If it is necessary to edit the .BAK file, rename the file giving it
    an extension other than .BAK. Or else, copy the file and give the
    copy a different filename extension.