INT 21 - Novell NetWare - FILE SERVER - DOWN FILE SERVER
        AH = E3h subfn D3h
        DS:SI -> request buffer (see below)
        ES:DI -> reply buffer (see below)
Return: AL = status
            00h successful
            C6h no console rights
            FFh files open
Desc:   take down the file server
Notes:  this function is supported by Advanced NetWare 2.1+
        the calling workstation must have SUPERVISOR privileges
SeeAlso: AH=E3h/SF=CBh,AH=E3h/SF=CFh,AH=E3h/SF=D1h

Format of request buffer:
Offset  Size    Description
 00h    WORD    0002h (length of following data)
 02h    BYTE    D3h (subfunction "Down File Server")
 03h    BYTE    flag: force down even if files open if nonzero

Format of reply buffer:
Offset  Size    Description
 00h    WORD    (call) 0000h (no results returned)