They have to stipulate their own classification to make their own purpose. Because sizes and shapes of AV materials vary too much among categories, most of libraries organize shelving first according to categories, and then to series number, while as a few of them, which collect only one categroy, shelve AV materials according to classification of content. The retrieval points are mainly those as classification, title, responsible body, shelfing number in the case of mannual retrieval. In addition to these points, other once, such as subject entry, key word, publisher are also applied when computerized retrieval is used. There are two kinds of AV service rooms, one delivers services to meet individual's needs, another to collective's.
Some libraries have several AV materials rooms with diferent functions, while some have only one.
Among all those in China, the National Library of China has the best AV in-room services. There are three AV Material Rooms in this library. One is for individual's pu rpose with 60 seats which delivers services of video, CD and sound cassette according to individual needs and choices. The other two are for collective's with together 200 seats, which deliver services of reader, slide, LD, CD, sound disc and videocassette, ect. Every wednesday, they offer to readers free of charge art film documentaries for operas, musics, dances, gallery collections or landscapes.