To extend or customize Bitrix Framework kernel and modules to your website, use the conventional system event handler technology.

In most cases, this technology is sufficient to fit the Bitrix Framework platform to any web project. However, if more substantial changes need to be made to implement features required by the website specifications and those changes simply cannot be done using existing event handlers, you may ask technical support to implement the required events.

Changing the Bitrix Framework kernel is strictly prohibited because any system update downloaded and installed using the SiteUpdate technology will overwrite the kernel irreversibly. Of course, you can update the kernel manually by checking the source code line by line and adding new lines - but doing so will be a calamity for you or system administrator. The rule is simple: resort to event handlers, or create a new module to implement any feature that cannot be done otherwise.

- Check that the website specifications include the description of event handlers that are used in the project. Such description should be kept up-to-date whenever any change is made to the existing event handlers, or a new event handler is added.