Some receivers provide to format parameters for each event it receive. You can specify the format inside a setting and a list of arguments from which extract value inside another setting. For more information on format see documentation of the String.Format method. The String.Format method receive a list of values which are describe in the list of arguments setting. Values come from three objects : the event, the event context and the receiver context. Only value from Get Properties on these objects can be used (not fields, not indexer). The event depends from your generator see the specific documentation of the event to kwnow available properties.
The list of arguments is a comma separated list of names. Each name is composed by two parts separated by a dot. The first part is the name of one of the three objects, the possible names are :

• Event : the event received by the receiver.
• ReceiverContext : the receiver context, this object is a ReceiverContext class.
• EventContext : the context of this event, this object is a EventContext class.

The String.Format method use a syntax {index[,alignment][:formatString]} which specifies a mandatory index. This index represent the order of the arguments in the list of arguments, the first argument has index 1, the second argument has index 2, .... The current date and time of the day is inserted at index 0.
A sample, the format "Event with identifier {1} from receiver {2} processed at {0:dd/MM/yyyy}" with argument list "Event.Id,ReceiverContext.Name" can give the result : "Event with identifier 3ff9eaf5-bea9-4647-b33a-fd8c3b3534c3 from receiver MyReceiverName processed at 15/06/2009"