@chapter Control Flow
@cindex control flow

The main program flow is defined by System class group.

@section The overview of control flow

This is main program flow for CUI system (using CParserSystem class).
@example
main (main function) 
   start_program (function in csystem.m)
     prologue (CParserSystem, CSystem)
       setupOption (CParserSystem (*1))
       startAnalysis (CParserSystem (*1))
       setHelpString (CParserSystem (*1))
       analyzeOption (CParsetSystem (*1))
      recoverPrologue (CSystem (*2))
     main (CSystem)
      recoverMain (CSystem (*2))
     epilogue (CSystem)
      recoverEpilogue (CSystem (*2))

(*1) means the method must be overridden by application specific system class.
(*2) the recovery method called when the fatal error (such as memory full)
     is occured. If the applicaton take cares  these errors, you must 
     override these method.

@end example

