This function should be called before either yaz_search() or yaz_present() to specify a range of records to be retrieved. The parameter start specifies the position of the first record to be retrieved and parameter number is the number of records. Records in a result set are numbered 1, 2, ... $hits where $hits is the count returned by yaz_hits().
如果成功则返回 TRUE，失败则返回 FALSE。