Rule 4:5-4 ("Affirmative Defenses; Misdesignation of Defense and Counterclaim") states that a responsive pleading "… shall set forth specifically and separately a statement of facts constituting "an avoidance or affirmative defense …." The comments and annotations to the Gann edition of the rules states that, ordinarily, affirmative defenses not pleaded (or otherwise timely raised) are deemed to be waived. Thus, it is obvious that careful attention needs to be given to the formulation of a responsive pleading lest the listing of an important defense be omitted.