INT 21 U - DOS 3.1+ internal - SERVER FUNCTION CALL                             
	AX = 5D00h
	DS:DX -> DOS parameter list (see #01686)
	DPLsee DOS Parameter List 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 (refer to BUGS: section 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 BootTo start up the computer or operating system. The term "boot" is a contraction of "bootstrap", which in turn comes from the expression "to lift oneself by one's boot straps."  The ROM BIOS on IBMInternational Busiuness Machines PCs and compatibles reads in the first sector of the disk, which contains a short (less than 500 bytes) program that reads in a portion of the operating system, which in turn reads in the remainder of the operating system.  See also IPL. 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 DPLsee DOS Parameter List, leading to problems for peer-to-peer
SeeAlso: AH=3Dh,AH=41h,AH=56h,AH=60h

Format of DOS parameter list:
Offset	Size	Description	(Table 01686)
 00h	WORD	AX
 02h	WORD	BX
 04h	WORD	CX
 06h	WORD	DX
 08h	WORD	SI
 10h	WORD	reserved (0)
 12h	WORD	computer ID (0 = current system)
 14h	WORD	process ID (PSPsee Program Segment Prefix 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