INT 21 - Far East DOS 3.2+ - GET DOUBLE BYTE CHARACTER SET LEAD TABLE
AX = 6300h
Return: AL = error code
00h successful
DS:SI -> DBCS table (see below)
all other registers except CS:IP and SS:SP destroyed
FFh not supported
Notes:  probably identical to AH=63h/AL=00h for DOS 2.25
the US version of MSDOS 3.30 treats this as an unused function,
setting AL=00h and returning immediately
the US version of DOS 4.0+ accepts this function, but returns an empty
list

Format of DBCS table:
Offset  Size    Description
00h  2 BYTEs   low/high ends of a range of leading byte of double-byte chars
02h  2 BYTEs   low/high ends of a range of leading byte of double-byte chars
...
N   2 BYTEs   00h,00h end flag

See also: 216300

216300 - Far East DOS 3.2+ - GET DOUBLE BYTE CHARACTER SET LEAD TABLE