CHECK Actions operate after the rule's right-hand-side phrase has matched.
The or action is the only specialized function built for this region. General NLP++ code serves to implement most CHECK Actions that you would want to perform.
Two special NLP++ functions operate in the CHECK Region. When a rule match is to be aborted, the function fail is called to accomplish this. To succeed without performing further checks, call the succeed function. Both of these can occur in other regions, but may operate differently. If succeed is executed, then element actions and POST Actions are performed next.