Library /sys$common/syshlp/mailhelp.hlb REPLY, Qualifiers, /LAST  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Specifies that the last message you sent will be used as text for
    the reply to the current message. You can use the /LAST qualifier
    with the /EDIT qualifier to edit the message before sending it.