This part of IEC 60118 specifies the electrical and mechanical requirements for an interface device to allow a general-purpose control device such as a desktop computer to be connected to hearing aids, for the purpose of electrical setting of their operating parameters. There is no specification of anything within the hearing aid, such as types of parameters and their signal processing characteristics, nor is there any specification of the parameter setting procedure – the method used to determine which settings are most appropriate to the person wearing the hearing aid. This standard is restricted to the digital interface between the control device and the hearing aid. This standard provides a specification such that all hearing aids which can be programmed by the specified digital interface may have their parameters set by a single control device and interface device. The specifications of this standard are for use in connection with hearing aids with parameters set by a direct electrical connection using a cable. They do not cover hearing aids with parameters controlled by radio frequency or infrared transmission, or any other "wireless" method of control.