Most of the work done in developing Z39.50 was carried out in the basic protocol framework. It becomes apparent that some problems would be quite unacceptable in implementing and reinforcing the networked information retrieval and that it needs some other arrangement such as ISP. This article discussed the current modifications like ISPs by reviewing the unique characters of Z39.50 and the overall design of a client-server search systems, and also distinguished the Z39.50 clients that have been developed as non-profits from those of profits in the perspective of Z39.50 function-expanding.