This part of IEC 60191 gives guidelines on the preparation of outline drawings of discrete devices. NOTE For preparation of outline drawings of surface mounted discrete devices, IEC 60191-6 should be referred to as well. The primary object of these drawings is to indicate the space which should be allowed for devices in an equipment, together with other dimensional characteristics required to ensure mechanical interchangeability. It should be noted that complete interchangeability involves other considerations such as the electrical and thermal characteristics of the semiconductor devices concerned. The international standardization represented by these drawings therefore encourages the manufacturers of devices to comply with the tolerances shown on the drawings in order to extend their range of customers internationally. It also gives equipment designers an assurance of mechanical interchangeability between the devices obtained from suppliers in different countries, provided they allow the space in their equipment that is indicated by the drawings and take note of the more precise information on bases, studs, etc. NOTE Additional details on the standardization philosophy used in this standard are given in Annex B.