INT 21 - Novell NetWare - MESSAGE SERVICES - ENABLE/DISABLE BROADCAST MESSAGES
        AH = E1h
        DS:SI -> request buffer (see below)
        ES:DI -> reply buffer
Return: AL = error code
Note:   these functions are supported by NetWare 4.0+ but are not listed in
          _NetWare_System_Calls--DOS_; they may be obsolete
SeeAlso: AH=E1h/SF=04h,AH=E1h/SF=09h

Format of request buffer:
Offset  Size    Description
 00h    WORD    length of following data (max 9Eh)
 02h    BYTE    subfunction
                02h disable station broadcasts
                03h enable station broadcasts
 03h    ???

Format of reply buffer:
Offset  Size    Description
 00h    WORD    (call) size of following results buffer
 02h    ???