Defining architecture-specific CPP macros

Step 1 places you in an environment where the C preprocessor, cpp, defines one or more architecture-specific symbols. On a Solaris 11 host, cpp defines the symbols __sun and __sparc. This, in turn, causes imake to generate many architecture-specific (machine-dependent) cpp macros:

#ifdef sun
#undef __sun
#define SunArchitecture                                   sun defined by C preprocessor
#ifdef mc68020
...
#endif 
#ifdef __sparc 
#undef __SunOS_5_11 
#undef __SunOS_5_10                                       sparc defined by C preprocessor imake defines longer symbols
#define MachineDep __SunOS_5_11 
#define machinedep __SunOS_5_10 
#endif ...