Format of parameter block for functions 4Ah and 6Ah:
Offset	Size	Description	)
 00h	WORD	length of data
 02h	WORD	code page ID (see #01757 at INT 21/AX=6602h)
 04h 2N BYTEs	DCBS (double byte character set) lead byte range
		  start/end for each of N ranges (DOS 4.0)
	WORD	0000h  end of data (DOS 4.0)