What goes into certified seed

by http://www.seedforthefuture.ca/what-goes-in-seed.aspx

Producing clean, pure and high quality Canadian certified seed requires a tremendous effort and investment – from plant breeders to seed growers to the licensed seed processing plants. Each bag of certified seed you purchase is not only an investment in your field today, but an investment to help take Canadian agriculture to the next level in innovation and productivity.

Whats in a bag of see?