/sys$common/syshlp/helplib.hlb DECnet-Plus, DCL Commands, SET, HOST, /VTP, Qualifiers, /LOG  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /LOG[=filespec]
       /NOLOG (default)

    Controls whether a log file of the entire session is kept. If you
    use the /LOG qualifier without the file specification, the log
    information is stored in the file SETHOST_VTP.LOG.