/sys$common/syshlp/helplib.hlb CMS, ANNOTATE, Qualifiers, /APPEND  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Controls whether CMS appends the history and source file listing
    to an existing file, or creates a new file. If you specify /APPEND
    and the output file does not exist, CMS creates a new file. If you
    do not provide an output file specification (see the description
    for /OUTPUT), CMS searches your default directory for a file with
    the element file name and the file type .ANN.