This image from the article explains it. http://static01.nyt.com/images/2015/06/01/us/visa-letter-alt-image-2/visa-letter-alt-image-2-articleLarge.jpg http://s

This image from the article explains it. http://static01.nyt.com/images/2015/06/01/us/visa-letter-alt-image-2/visa-letter-alt-image-2-articleLarge.jpg http://static01.nyt.com/images/2015/06/01/us/visa-letter-alt...