Preheat broiler. Split pitas horizontally into 2 rounds. Spread rough edges with margarine. Place on cookie sheet. In a small bowl, toss together oregano and Parmesan cheese. Sprinkle over margarine. Cut each bread into wedges. Broil about 13 cm from heating element until crisp, about 2 minutes. Watch carefully! VARIATIONS: experiment with other herbs of your choice such as chives and parsley; or, omit oregano and sprinkle with sesame seeds. Serve alone or with dips or pates.