This International Standard specifies a method for the determination of price indexes relating to the prices of print and electronic media acquired by libraries. It is not meant for calculating a price index of the national media production. The media included are restricted to books, serials and databases. NOTE Further details are given in 2.2 and 3.1. It is intended primarily for use by the library community, although it is accepted that other organizations may also find it useful. It focuses on compiling price indexes on the base of national and international sources, relevant to one country or region and different types of libraries. Different indexes will be appropriate to different types of library, according to the types of material in their collections. This International Standard presents a methodology allowing for a general index which could be calculated from subsets of data, and could be weighted according to local needs. It introduces sampling methods for the selection of materials on which to base calculations. Note that this International Standard describes indexes of prices, not of costs. Local cost indexes can be compiled instead of price indexes where there is insufficient uniformity of pricing structures to permit the calculation of price indexes, or as an additional tool for libraries. Guidelines for the calculation of local cost indexes are given in Annex B.