This is another type of short-hand label similar in its use and interpretation to the Punched Labels shown earlier. Each series of notches tells a different story, and the key to their interpretation is found in the record books. Two notches, for example, might represent the Alaska daisy and three notches the variety named Westralia. The top label above would then record the hybridizing of these two varieties. (The small notches for the string are not counted.) Mr. Burbank finds this method of keeping track of experiments highly satisfactory.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 3 Chapter 8