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

       /WRITE_CHECK
       /NOWRITE_CHECK (default)

    Reads each record in the output file after it is written to
    verify that the record copied successfully and that the file
    can be read subsequently without error.

                                   NOTE

       Some hardware devices, such as TK50 tape drives, verify data
       integrity as part of their hardware function. For devices
       such as these, you do not need to use /WRITE_CHECK. For
       information about which devices provide automatic write
       checking, consult your hardware documentation.