subcommand

    Defines the specific operation to be performed.

 filespec

    Specifies the device name, directory, and file name for the
    EXCHANGE input or output device. It has the following general
    form:

    device:[directory]filename.filetype;version

    device:    The device name can be either a standard OpenVMS
               device name of the form ddcu: or a logical name that
               translates to an OpenVMS device name. If the device
               field is omitted for a reference, the current default
               device is assumed. When a virtual device is mounted, a
               name is created for the virtual device and is used as
               the device name in subsequent EXCHANGE commands.

    [directory]The syntax of the directory subfield is volume
               specific.

    filename   The name field file specification for an input or
               output file. The exact format allowed for the file
               name is dependent on the volume format qualifier used.

    filetype   The extension field of the file specification.

    version    The version number of the file, if supported by the
               volume type.