The @ (at sign) command reads and executes the CDO commands
    contained in the specified file as if you had entered these
    commands at the terminal. The file can contain any valid CDO
    commands, including other @ commands.

    By default, CDO does not echo commands and comments in your file
    to the standard output location. You can override this default
    by including the SET VERIFY command as the first command in your
    file.

    By default, CDO exits the file when it encounters an error. You
    can override this default by including the ON command in your
    file.

    When CDO executes an EXIT command in the file, or reaches the end
    of the file, control returns to the command stream that invoked
    the file. That command stream can be the terminal or a previous
    file containing CDO commands. You can issue the @ command at the
    CDO prompt (CDO>). After the CDO commands execute, the CDO prompt
    returns.

    You can issue the @ command as a foreign command at the system
    level. You can append the @ command to the REPOSITORY OPERATOR
    command. You can also include the REPOSITORY OPERATOR @ command
    in an OpenVMS command procedure.

    To execute a CDO command procedure with a default file type of
    .CDO, you do not need to specify the file type.

    If the file type for a CDO command procedure is not .CDO, you
    must specify the file type to execute the command procedure.

    After the CDO commands execute, the system prompt returns. If
    you intend to use your file as an initialization file, you need
    not issue the @ command. Instead, name your file CDO$INIT.CDO
    and place it in the directory from which you invoke CDO. CDO
    then automatically executes this file at the start of each CDO
    session.

    You can also define CDO$INIT as a logical name specifying a
    device, directory, and file name. If you use such a logical name,
    the file does not need to be in your default directory when you
    invoke CDO.