Whenever copies of non-patent literature items are included in the search files, they are stored together with the patent documents with the same classification, usually in separate folders (see IX, 2.5). Since experience shows that the importance of many of these non-patent items for purposes of search decreases strongly after a few years (e.g. five years), those that have lost interest can be removed. The periodicals and other non-patent items themselves are stored in library manner and will be kept somewhat longer (e.g. 10 years) for the purpose of later consultation and copying. These items are stored together with non-patent literature kept for other purposes as indicated in IX, 5.