[en] Retrieval performance by the weighting scheme developped is demonstrated with a set of 10 search topics and 33,614 documents for half a year in the INIS data base. Conventional man prepared medium or tighter queries are clearly superior to weighted loosest queries but slightly inferior to weighted looser ones in average performance. The weight generation sample extracted within the limits of 100 documents from a data file for over two months can be roughly applied to weighting in another residual file and a more realistic data file of 241,708 documents for three and a half years. It is tried to estimate approximately the degrees of improvement in precision and loss in recall at each ranked score position in other weight applied outputs, from rank-precision curves for some weight generation samples. This relevance ranking scheme leads to considerable benefits in practical query formulation. Compared with the present weighting of both manually indexed and machine up-posted terms, weighting of manually indexed terms only may possibly bring about a much more promising application of the scheme. (author)