This HowTo assumes that you have a smattering of ACL in general and of how the acl-extension works basically. It will introduce you into the abstract and give you a hint on how to use Business-Rules. If you have in-depth questions, please refer to the extension documentation.
Using ACL in an RBAC-manner cannot and should never obscure the fact that the underlying system is still ACL-based. In fact, the Business-Rules are just another layer in the permission-check plan.
Countries sometimes change their laws pertaining to timezones and daylight saving times. This means that GMT+2 can be a different time this August compared to last August! However, by using php's DateTime class (instead of timestamps), we can do both "format" and "timezone" conversions on a single DateTime object (only 2 lines of code) for date, time, timestamp and datetime types - while php takes care of nightmares such as current and historical timezones and daylight saving times.
CFormatter is one of Yii's core components and used to format values displayed in widgets like CGridView or CDetailView. All classic formats like numbers, text, urls or datetime are supported but you may have to use a formatting rule that isn't built in. Let's say we want to display arrays of strings (like tags associated with a product model). When using CDetailView we would usually make use of PHPs implode function to create a simple string value of all values in the $product->tags array.