8.1.1 Include Files and Libraries All the C code that uses the REXX application interface, must include a special header file that contains the necessary definitions. This file is called rexxsaa.h. Where you will find this file, will depend on you system and which compiler you use. Also, the interface part between the application and the REXX interpreter may be implemented as a library, which you link with the application using the functions described in this chapter. The name of this library, and its location might differ from system to system. Under Unix, this library can be implemented as a static (libregina.a) or dynamic library (libregina.[so|sl]). Under other platforms Regina is also be implemented as a static or dynamic library.