Introduction - If you have any usage issues, please Google them yourself
Due to copyright restrictions of zb4, although there a lot of people involved in the expansion period (based on zb4 rewriting) preparation, officially released the code is completed by the zero a person to write.
So in the upgrade and patch is not perfect, and not all zb4 derived code based on perfect management.
Xe aside the drawbacks of these type locking policy, everybody can participate in the development and can constantly upgrade, and improve the patch release measures of open source development scheme.
There are many people involved in making the program itself has a fast upgrade program, without copyright marked open source policy enables developers and users can put more energy to the site management and maintenance.