Refuge-in-a-bag, refuge in 2 bags, reduced refuge are all terms being used this fall about different Bt corn hybrids. If you are confused by all of the information, like me, there is an excellent resource that breaks down the latest information, and refuge requirements for the various Bt events.
Dr. Ric Bessin, Extension Entomologist, has updated Bt-corn for Corn Borer Control (ENTFACT 118), which is available online in the html version and in the pdf version.
He includes a table that breaks down all of the Bt events, the companies, the trade names (i.e. YieldGard, Herculex, Viptera, etc.), the pests controlled and the refuge required. This table will be a tremendous help as you try to sort through the Bt "maze".