Just as Closed Captioning helps the hearing impaired understand films, Audio Description (also known by the WGBH/ PBS-given name Descriptive Video Service) helps the visually impaired. This is aired on what is called a "secondary audio program" channel, or SAP. However, Congress finally passed a little-known and publicized bill in 2010 to allow the FCC to do the above, and beginning July 1, 2012, a slow-phase in of required description will begin across the country until the top sixty markets have it in 2017.