The ESL APPC DLL has a corresponding include file that you must reference in your ESL program before you can invoke any of the APPC subroutines in the DLL.

Your ESL program must contain the following line:

include "eslappc.inc" 

The include file declares the ESL APPC subroutines and argument types. It also contains definitions for ESL APPC integer constants, which are used both to set variables for some subroutine calls and as identifiers for ESL APPC event notifications.