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

       /DATA_CHECK[=([NO]READ,[NO]WRITE)]

    Specifies whether a read data check (rereading each record), a
    write data check (reading each record after it is written), or a
    combination of the two is performed on the file during transfers.
    By default, a write data check is performed.