Int 21 Fn 5D00  U - DOS 3.1+ Internal - Server Function Call               [D]

   AX = 5D00h
   DS:DX -> DOS parameter list (see below)
   DPL contains all register values for a call to INT 21h

Return: as appropriate for function being called

Notes: does not check AH.  Out of range values will crash the system
   executes using specified computer ID and process ID
   sharing delay loops skipped
   a special sharing mode is enabled to handle FCBs opened across network
   wildcards are enabled for DELETE (AH=41h) and RENAME (AH=56h) under
     MS-DOS; under DR-DOS 3.41, wildcards corrupt the filesystem; and
     under DR-DOS 5.0-6.0, the call returns error code 03h due to improper
     support for the server function call (see below)
   an extra file attribute parameter is enabled for OPEN (AH=3Dh),
     DELETE (AH=41h), and RENAME (AH=56h)
   functions which take filenames require canonical names (as returned
     by AH=60h); this is apparently to prevent multi-hop file forwarding
BUGS:  the OS/2 2.0 DOS Boot Session incorrectly maps DOS drive letters,
     seemingly ignoring HPFS drives
   DR-DOS 5.0-6.0 merely recursively call INT 21 after loading the
     registers from the DPL, leading to problems for peer-to-peer
     networks

See Also: AH=3Dh,AH=41h,AH=56h,AH=60h

Format of DOS parameter list:
Offset Size    Description
 00h   WORD    AX
 02h   WORD    BX
 04h   WORD    CX
 06h   WORD    DX
 08h   WORD    SI
 0Ah   WORD    DI
 0Ch   WORD    DS
 0Eh   WORD    ES
 10h   WORD    reserved (0)
 12h   WORD    computer ID (0 = current system)
 14h   WORD    process ID (PSP segment on specified computer)

Note:  under Windows Enhanced mode, the computer ID is normally the virtual
     machine ID (see INT 2F/AX=1683h), though this can reportedly be
     changed by setting UniqueDOSPSP= in SYSTEM.INI