INT 21 - CED (Command EDitor) - INSTALLABLE COMMANDS
AH = FFH
AL = subfunction
00h add installable command
BL = mode - bit 0 = 1 callable from DOS prompt
bit 1 = 1 callable from application
DS:SI -> CR-terminated command name
ES:DI -> FAR routine entry point
01h remove installable command
DS:SI -> CR-terminated command name
02h reserved, may be used to test for CED installation
Return: CF clear if successful
CF set on error
AX = 01h invalid function
02h command not found (subfunction 01h only)
08h insufficient memory (subfunction 00h only)
0Eh bad data (subfunction 00h only)
AH = FFh if CED not installed
Note:   CED is a shareware DOS command-line enhancer by Christopher J. Dunford

See also: 210A00

21FF - CED (Command EDitor) - INSTALLABLE COMMANDS