SANTA ANA Within the forbidding walls of the Supermax federal prison, where high-profile inmates live in heavily guarded isolation, a section was created in 1998 called "H Unit," where six special prisoners could mingle, use a computer and share information, a prison official testified Wednesday. The six men, dropouts from the notorious Aryan Brotherhood prison gang, were known as "cooperators" or in slang as "snitches." Danny Shoff, a Bureau of Prisons official now assigned to Washington, D.C., said he was one of the few staff members at the Florence, Colo., facility allowed entry to "H Unit" during the period that...