Conversely, by simply giving any Action a Definition name it becomes a definition, therefore no longer a directly executable action. For example,

OUTPUT(Person);

is an action, but

Attr4 := OUTPUT(Person);

is a definition and does not immediately execute when submitted as part of a query. To execute the action inherent in the definition, you must execute the Definition name you've given to the Action, like this:

Attr4;    // run the previously defined OUTPUT(Person) action