0) Debug folder used to hold a debugging library of yacco2 API 1) U can turn on dynamic tracing facilities of Yacco2 or add your own tracing stuff within yacco2's *w code 2) Regen wlibrary.w code using as an example bld_bash_APPLE script. Other scripts GNU and Solaris hold. Look at the comments within this script to see Debug comments 3) Recompile yacco2 library and place it in this folder 4) Make sure u link your program against this debug library You can also modify the *w source code per o2, o2linker, and rebuild the Yacco2 project to do dynamic tracing. If u suspect Yacco2's grammars are suspect, then put in your own tracing facilities and rebuild them. Have a read compiler/grammars/makefile_APPLE Please read o2book.pdf for more comments on tracing facilities.