INT 7A O - PRINDIR - 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. (moved to INT 7C, then INT 2F/AX=7F00h)
SeeAlso: INT 7C"PRINDIR",INT 2F/AX=7F00h"PRINDIR"