The grammar element for a custom event must have a special id: the prefix event-message- followed by the JMS message type string for the event. The <element-icon> and <declared-message-type> tags must also be used to provide an icon (specified as a class loader resource path) and the message type that will be associated with the event. The icon is optional; a generic icon will be used if none is specified. For instance, if you were defining an expression for the custom event MyProject.MyEvent, you would define the event in the grammar as follows:

<sequence id="event-message-MyProject.MyEvent">
  <element-icon>icon-resource-path</element-icon>
  <declared-message-type>MyProject.MyEvent</declared-message-type>
  ...
</sequence>