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.
Effect of market
Index growth or the actual value rise, exceeding the forecast is a positive sign for Euro.
In case of significant forecast variations may have a strong influence on the European currency dynamics.