了解一个情报检索系统是如何运行的,对于检索人员和该系统的生产者、建立者都有帮助。就生产者来说,性能水平可作为改进设计的基础。就检索人员来说,使用一个系统的特长可提高检索的有效性。手工标引,即给一篇文献标引主题 Knowing how an information retrieval system works is helpful to both the searcher and the producer and creator of the system. As far as the producer is concerned, the performance level can serve as a basis for improving the design. For the searcher, using a system’s expertise can increase the search’s effectiveness. Manual indexing, that is, to a document indexing theme