In medium bowl, combine salad dressing, vinegar, sugar, mustard, celery seed, mustard seed, and pepper. In large bowl combine cabbage, carrots, and parsley. Pour dressing mixture over cabbage mixture and toss gently to coat. Cover, refrigerate overnight or until serving time, at least 2 hours. Note: I use refrigerated buttermilk spice ranch style dressing such as Marie's, Hartville Kitchen's, etc.