Messaging Events can also cause triggers to start.

Here, the system takes into account MQTT’s wildcard capability. When creating triggers for Publish, Subscribe, and Unsubscribe, you can pass in the topic filter as a topic commands (ie, it can contain the ‘#’ and ‘+’ path elements). See the Topics documentation for a description of wildcards.

Of course, if you don’t use wildcards, the match must be exact. If, for any of events (Publish, Subscribe, and Unsubscribe), you do not provide a topic, all such events will match and fire your trigger.