VMS Help WRITE, Qualifiers, /ERROR  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /ERROR=label

    Transfers control on an I/O error to the location specified by
    label (in a command procedure). If no error routine is specified
    and an error occurs during the writing of the file, the current
    ON condition action is taken. The /ERROR qualifier overrides any
    ON condition action specified. If an error occurs and control
    passes successfully to the target label, the reserved global
    symbol $STATUS retains the error code.