MAIL$_MAILFILE_DEFAULT_NAME

    MAIL$_MAILFILE_DEFAULT_NAME specifies the default mail file
    specification MAIL$MAILFILE_INFO_FILE should use when opening
    a mail file. The buffer address field of the item descriptor
    points to a character string of 0 to 255 characters that defines
    the default mail file specification.

    Specify a value from 0 to 255 in the buffer length field of the
    item descriptor.

    If you specify the value 0 in buffer length field of the item
    descriptor, MAIL$MAILFILE_INFO_FILE uses the current default
    directory as the default mail file specification.

    If you do not specify MAIL$_MAILFILE_DEFAULT_NAME, MAIL$MAILFILE_
    INFO_FILE creates the default mail file specification from the
    following sources:

    o  Disk and directory defined in the caller's user authorization
       file (UAF)

    o  Subdirectory defined in the Mail user profile

    o  Default file type of .MAI

 MAIL$_MAILFILE_FOLDER_ROUTINE

    MAIL$_MAILFILE_FOLDER_ROUTINE specifies an entry point longword
    address of a user-written routine that MAIL$MAILFILE_INFO_FILE
    should use to display folder names. MAIL$MAILFILE_INFO_FILE calls
    the user-written routine for each folder in the mail file.

 MAIL$_MAILFILE_NAME

    MAIL$_MAILFILE_NAME specifies the name of the mail file to be
    opened. The buffer address field points to a buffer that contains
    a character string 0 to 255 characters long.

    Specify a value from 0 to 255 in the buffer length field of the
    item descriptor.

    If you do not specify MAIL$_MAILFILE_NAME, the default mail file
    name is MAIL.

 MAIL$_MAILFILE_USER_DATA

    MAIL$_MAILFILE_USER_DATA specifies a longword that MAIL$MAILFILE_
    INFO_FILE should pass to the user-defined folder name action
    routine.

    This item code is valid only when used with the item code MAIL$_
    MAILFILE_FOLDER_ROUTINE.

 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.