A product is labeled 72% cocoa. What does this refer to? How does this percent differ from the percent cocoa butter or cocoa solids nonfat in a product? How does milk chocolate compare with...

A product is labeled 72% cocoa. What does this refer to? How does this percent differ from the percent cocoa butter or cocoa solids nonfat in a product?

How does milk chocolate compare with bittersweet chocolate in minimum percentage of cocoa solids in the U.S.? In Canada?