An interactive search and editing system, 3RIP, is being developed at the library of the Royal Institute of Technology in Stockholm for large files of textual and numeric data. A substantial part (on the order of 10-E9 characters) of the primary file of the search system will consist of bibliographic references from a wide range of sources. If the performance of the search system is to be satisfactory, all of the primary file, or at least a large part of it, should be stored on fairly expensive secondary storage devices with relatively short access time. In order to reduce the considerable costs associated with the storage of the primary file two different approaches might be attempted: to use cheaper storage devices with longer access time for those parts of the primary file that rarely have to be processed, or use a more efficient way of coding the primary file instead of the conventional coding method. (Author)