In the Advanced menu of the Triggers tab in the Actions dialog is Custom Trigger. This trigger allows you to enter your own name for a trigger that can then be activated using a Custom Action or the TriggerComponentEvent function.

For example, if you create a Custom Trigger named PlaySequence on a Frame object named Start, the following line of code will trigger StartSequence and run the actions listed under it

Start.TriggerComponentEvent("PlaySequence")

Search for Custom Trigger in the main Opus Help file for more information.