29.9.2001 Official Journal of the European Communities L 261/49 COMMISSION REGULATION (EC) No 1921/2001 of 28 September 2001 laying down detailed rules for the implementation of Council Regulation (EC) No 2494/95 as regards minimum standards for revisions of the harmonised index of consumer prices and amending Regulation (EC) No 2602/2000 (Text with EEA relevance) THE COMMISSION OF THE EUROPEAN COMMUNITIES, (7)  There is considerable scope for procedural differences Having regard to the Treaty establishing the European Community, Having regard to Council Regulation (EC) No 249495 of 23 October 1995 concerning harmonised indices of consumer prices (!), as last amended by Commission Regulation (EC) No 1617/1999 (3, and in particular Article 4 and Article 5(3) thereof, Having regard to the opinion of the European Central Bank (%), Whereas: (1) By virtue of Article 5(1)(b) of Regulation (EC) No 2494/ 95, each Member State is required to produce a harmo- nised index of consumer prices (HICP) starting with the index for January 1997. (2) It is particularly important to secure a high degree of credibility of the HICP which may be supported by the objective of limiting in a given context the number of HICP revisions to the minimum extent necessary. (3) It is generally accepted that the annual average, annual and monthly rates of change of the HICPs are important for the measurement of inflation, more particularly for assessing price convergence and informing the monetary policy of the European Central Bank. (4)  Changes in the system of national or harmonised rules constitute valid reasons for revisions to the HICPs to the extent that they ensure or improve the comparability, reliability, or relevance of the HICPs; changes in the system of harmonised rules should not require revisions unless otherwise stated in the context of particular implementing measures. (5)  Article 6 of Commission Regulation (EC) No 2602/2000 of 17 November 2000 laying down detailed rules for the implementation of Council Regulation (EC) No 2494/95 as regards minimum standards for the treatment of price reductions in the harmonised index of consumer prices (¥) needs to be amended accordingly. (6)  Revisions due to mistakes, or because of new or improved basic information are valid reasons for revi- sions to HICPs because they improve the comparability, reliability, or relevance of the HICPs. 257, 27.10.1995, p. 1. 192, 24.7.1999, p. 9. 244, 1.9.2001, p. 5. 300, 29.11.2000, p. 16. LLeoee A between Member States on the revision of index series. A set of harmonised rules is necessary to ensure that the resulting HICPs meet the comparability requirement of Article 4 of Regulation (EC) No 2494/95 as well as their reliability and relevance. (8)  The measures provided for in this Regulation are in accordance with the opinion of the Statistical Programme Committee established by Council Decision 89/382/EEC, Euratom (%), HAS ADOPTED THIS REGULATION: Article 1 Aim The aim of this Regulation is to provide information on signifi- cant effects of implementing measures under Regulation (EC) No 2494/95 and to establish harmonised rules concerning revisions to the HICP that are consistent with those measures, and sufficient to ensure their comparability, reliability, and relevance. Article 2 Definitions For the purpose of this Regulation the following definitions shall apply: (a) a ‘revision’ is an ex-post change in a HICP series, index level, rate of change or weight, that has been made publicly available through printed or electronic media by the Commission (Eurostat) affecting the results to one decimal place; (b) a ‘mistake’ is an unintentional breach of an established rule affecting at least one HICP series; (c) a ‘provisional’ result is a result which is, subject to revision, expected to be finalised in a later month. Article 3 Revisability 1. The officially published HICP series may be revised. () O] L 181, 28.6.1989, p. 47.