Sometimes it's desirable to have more control over the current date/time and to use an alternate date/time for the execution (for example, if you want to see what will happen during generation on a future date).

The engine and execution context both contain a ExecutionDateTime property that is always set to the current local date/time (I.e. DateTime.Now). However, all code and themes should use the GetCurrentDateTime() extension method that's available on the engine and execution context anywhere the current date/time is needed. This extension method also checks the setting CurrentDateTime and will use that value if it's set instead of the absolute local date/time. This allows you to "override" the current date/time for the execution by setting CurrentDateTime in your settings file or via the bootstrapper.