It is the consumer prices index, excluding the volatile energy and food items costs.
The Central Bank often uses exactly this index on mid-term prospects (3-6 months) as inflationary target level inflation in the country.
The index calculation unadjusted for the highly volatile components allows for the correct estimation of inflation rate changes for an accounting period.
However, also worth mentioning that the excluded components comprise a quarter of the overall volume and the goods, accounted in the index calculation, having a significant influence on the other groups of products.
Effect of market
The index growth or the actual value rise, exceeding the forecast is a positive sign for the Dollar.
Significant forecast variations may have a strong influence on the American currency dynamics.