If the next input token does not match any of the alternative labels of the choice, execution continues with the first action in the otherwise alternative. If the otherwise alternative is taken, the input token is not accepted from the input stream, but remains as the next input token. After execution of the last action in an alternative of the choice, execution continues following the choice. If the next input token does not match any of the alternative labels and no otherwise alternative is present, a syntax error is flagged. Form 7 is a call to a procedure rule.
Execution continues at the first action in the specified rule.
Form 8 is a return action. It causes a return from the procedure rule in which it appears. A procedure rule may return explicitly by executing a return action or implicitly by reaching the end of the rule. Form 9 is a rule choice. Execution continues with the first action of the alternative whose label matches the returned value.