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

       /ERASE_ON_DELETE
       /NOERASE_ON_DELETE (default)

    Determines whether the space occupied by a file is overwritten
    with a system-specified pattern when a file on the volume is
    deleted.