COS is really an advaced topic and there was not enough time to completely cover all the topics in the JRE course and the labs without severly rushing and holding to a very tight time management schedule. The topic was removed to the Appendix. You should always check the Exam topics to see what will be covered in the Exam. information in the Appendices are almost always covered in teh Exams. if you need more inforamtion, you can take this question to the Certification forum.