MAIL$_MESSAGE_BACK

    When you specify Boolean item code MAIL$_MESSAGE_BACK,
    MAIL$MESSAGE_INFO reads the identification number of the current
    message and returns the preceding message.

    Specify the value 0 in the buffer length and buffer address
    fields of the item descriptor.

    Do not specify MAIL$_MESSAGE_BACK, MAIL$_MESSAGE_ID, and MAIL$_
    MESSAGE_NEXT in the same call to MAIL$MESSAGE_INFO.

 MAIL$_MESSAGE_ID

    MAIL$_MESSAGE_ID specifies the message identification number of
    the message on which the operation is to be performed. The buffer
    address field of the item descriptor points to a longword that
    contains the message identification number.

    Do not specify MAIL$_MESSAGE_BACK, MAIL$_MESSAGE_ID, and MAIL$_
    MESSAGE_NEXT in the same call to MAIL$MESSAGE_INFO.

 MAIL$_MESSAGE_NEXT

    When you specify the Boolean item code MAIL$_MESSAGE_NEXT,
    MAIL$MESSAGE_INFO reads the message identification number of
    the current message and returns the message that follows it.

    Specify the value 0 in the buffer length and buffer address
    fields of the item descriptor.

    Do not specify MAIL$_MESSAGE_BACK, MAIL$_MESSAGE_ID, and MAIL$_
    MESSAGE_NEXT in the same call to MAIL$MESSAGE_INFO.

 out_item_list

    OpenVMS usage:itmlst_3
    type:         longword
    access:       write only
    mechanism:    by reference
    Item list specifying the information you want the routine to
    return. The out_item_list argument is the address of a list of
    item descriptors, each of which describes an item of information.
    The list of item descriptors is terminated by longword value of
    0.