Before April 2002, AP was provided through the State Earnings-Related Pension Scheme, (SERPS). SERPS was a career average pension scheme, based on the band of earnings each year between a "LEL" or '"Lower Earnings Limit"' (£5,304 in 2011/12) and a "UEL" or '"Upper Earnings Limit"' (£42,475 in 2011/12). Any SERPS entitlement already built up is retained and revalued each year in line with the changes in average earnings (that is, in "real" terms) until State Pension Age. It is then added to any Basic State Pension payable, and the combined amount uprated thereafter in line with the index of retail prices (RPI).