This part of IEC 60127 relates to universal modular fuse-links (UMF) for printed circuits and other substrate systems, used for the protection of electric appliances, electronic equipment, and component parts thereof, normally intended to be used indoors. It does not apply to fuse-links for appliances intended to be used under special conditions, such as in a corrosive or explosive atmosphere. These fuses are normally intended to be mounted or replaced only by appropriately skilled persons using specialized equipment. This standard applies in addition to the requirements of IEC 60127-1. The objectives of this part of IEC 60127 are as given in IEC 60127-1, with the additional requirement of a degree of non-interchangeability.