Hi everyone! I am 15 years old and an aspiring baker. While looking through a Culinary textbook from the Culinary Institute of America that my uncle gave me, I came across a recipe entitled "Chocolate XS Cake". Unable to find a description within the book, I was hoping someone here could help me. What does "XS" stand for? Surely it does not mean extra small. What makes this cake different from any other chocolate cake? Thank you!