Years ago when it was packaged in glass the label on Miracle Whip included the words "salad dressing".
https://c1.staticflickr.com/3/2715/4...13d_z.jpg?zz=1
I too agree that they used Miracle Whip but did not want to use the brand name in the printed book. Since this is a recipe for chicken salad you could use Miracle Whip, your favorite brand of mayo or homemade mayonnaise.