It describes important background material used during the revision of IEC 61196-1:1995, Clause 14, Guidance for surface transfer impedance and screening attenuation limits for flexible r.f. cables. It is also given the relationship between surface transfer impedance (ZT) and screening attenuation (as), also measurements of ZT and as are provided to show the correlation of mean screening attenuation between 200 MHz and 500 MHz and ZT at both 30 MHz and 300 MHz.