A method and arrangement for estimating line insertion loss of a customer transmission line at a frequency or a plurality of frequencies. In the preferred embodiment, educational material is provided at a child’s local computer under control of a central computer system connected to it over a computer network. The client requests a license server to transmit the license identified by the license-identifying information. The SN is scalable for large sized sets of conductors and can be used hierarchically in, for example, an integrated circuit or in an electronic system. Pharmaceutical compositions comprising such compounds and methods of treatment using such compositions are also disclosed.