
Article 1 
The aim of this Regulation is to ensure that the HICPs are constructed using weightings which are sufficiently reliable and relevant for the purpose of international comparisons.
Article 2 
For the purpose of this Regulation, the ‘weighting reference period’ of an HICP is defined as the 12-month period of consumption or expenditure from which the weightings are estimated for the compilation of the latest HICP index figure. ‘Sub-indices’ are as defined in Commission Regulation (EC) No 2214/96.
Article 3 

1. Each month Member States shall produce HICPs using weightings which reflect consumers' expenditure patterns in a weighting reference period ending no more than seven years before the preceding December.
2. Each year, Member States shall carry out a review of weightings in order to ensure that they are sufficiently reliable and relevant to meet the comparability requirement established in Article 4 of Regulation (EC) No 2494/95. The review may be confined to weightings at the level of sub-indices and their major components.
3. In the review, Member States shall check whether or not there have been any important changes since the weighting reference period in current use regarding price developments of each major component index relative to the HICP, or sustained market developments in each major component group.
4. Where reliable evidence shows that changes referred to in paragraph 3 indicate a weighting change that would affect the change in the HICP by more than 0,1 percentage point on average over one year against the previous year, Member States shall adjust the weightings of the HICP appropriately. Member States shall not be obliged to take account of any changes occurring within a two-year period ending in December before the review.
5. Any adjustments made pursuant to paragraph 4 shall be implemented by Member States, at the latest, in the index for January following the year of the review.
Article 4 
Member States shall provide the Commission (Eurostat) at its request with sufficient information on the weightings used to construct the HICP including the weighting reference period used, the outcome of the annual review and the adjustments made for compliance with this Regulation to be evaluated.
Article 5 
This Regulation shall enter into force on the 20th day following its publication in the Official Journal of the European Communities.
This Regulation shall be binding in its entirety and directly applicable in all Member States.Done at Brussels, 10 December 1997.
For the Commission
Yves-Thibault DE SILGUY
Member of the Commission