OutputtableTraittoo. And just like with the local action traits, the concepts explained here apply to all defined actions (you just need to use the corresponding extension trait).
my_output_extension. The name of the method is derived from the name of the trait. Basically these are the rules:
Trait, it is removed.
MyOutputExtensionTrait, the method must be named
my_output_extension. If you misname it, it will simply be ignored.