INT 21 U - LAN Manager Enhanced DOS - REMOTE API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running. Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes. CALL AX = 5F3Fh CX = api number ES:DI -> data descriptor ES:SI -> parameter descriptor ES:DX -> auxiliary descriptor (if DX <> 0) ??? Return: ???