PR QR codes keep pace as mobile proliferates Those black-and-white bar-code squares on ads are a versatile way to enhance information and deliver it anywhere. By Matt WilsonMarch 4, 2011 SHARE To read the full story, log in. Become a Ragan Insider member to read this article and all other archived content. Sign up today Already a member? Log in here. Learn more about Ragan Insider.