CPI

Consumer Prices Index. This is the current measure of inflation that the government has decided to use to ensure benefits from LGPS 1998, 2009 and 2015 keep pace with increases in the cost of living.
 
The amount of pension in your Pension Account at the end of each scheme year will be adjusted in line with the cost of living - as currently measured by the Consumer Prices Index (CPI) - to ensure it keeps its value.