INT 2F U - DOS 3.3+ internal - INSTALLABLE COMMAND - EXECUTE                    
	AX = AE01h
	DX = magic value FFFFh
	CH = 00h
	CL = length of command name (4DOS v4.0)
	DS:BX -> command line buffer (see #02977)
	DS:SI -> command name buffer (see #02978)
Return: DS:SI buffer updated
	  if length byte is nonzero, the following bytes contain the uppercase
	  internal command to execute and the command line buffer contains the
	  command's parameters (the first DS:[SI] bytes are ignored)
Notes:	this call requests execution of the command which a previous call to
	  AX=AE00h indicated was resident
	APPEND hooks this call
BUG:	Novell DOS 7.0's COMMAND.COM (prior to Update 12) will attempt to run
	  a disk program with the indicated name even if the returned length
	  byte is zero, because the register used to flag this case is
	  clobbered without first checking it.	The workaround is to set the
	  command name buffer to "REM" followed by enough blanks to pad out
	  the original command's length, which will also work with MS-DOS 6.
	  (from padgett@tccslr.dnet.mmc.com)
SeeAlso: AX=AE00h