"The SIV [special immigrant vias] programs, in their current forms, are the product of a series of legislative provisions enacted since 2006. These provisions make certain Iraqis and Afghans who have worked as translators or interpreters, or who were employed by, or on behalf of, the U.S. government in Iraq or Afghanistan, eligible for special immigrant visas (SIVs). Special immigrants comprise a category of permanent employment-based admissions under the Immigration and Nationality Act. Upon admission to the United States, special immigrant visa holders become LPRs [lawful permanent residents]. (The SIV programs are separate from the U.S. refugee admissions program.)"
CRS Insight, IN10649
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html