For a cow, aAa® and Weeks®  Analysis numbers show the qualities she needs, in order of priority, from left to right. The numbers 435, for example, show that a cow needs  aAa® and Weeks® qualities #4 Strong, #3 Open, and #5 Smooth.

For a bull, aAa® and Weeks®  Analysis numbers show the qualities he adds in a mating, in order of priority, from left to right. For example, the numbers 435216 show that a bull adds  aAa® and Weeks® qualities #4 Strong, #3 Open, #5 Smooth, #2 Tall, #1 Dairy and #6 Style.

Matching a cow’s aAa® and Weeks®  Analysis numbers with those of a bull will increase the odds of improving the next generation and of getting an above average daughter of the bull used. For example, when a cow is analyzed as needing  aAa® and Weeks® qualities 435, Strong, Open and Smooth, consider using bulls with aAa® and Weeks® qualities 435, 453, 345, 432, 543, 354, or 534 as his first three numbers.

Source:  http://aaaweeks.com/