IEC 60751:2008 specifies the requirements and temperature/resistance relationship for industrial platinum resistance temperature sensors later referred to as "platinum resistors" or "resistors" and industrial platinum resistance thermometers later referred to as "thermometers" whose electrical resistance is a defined function of temperature. Values of temperature in this standard are in terms of the International Temperature Scale of 1990, ITS-90. Temperatures in degrees Celsius are denoted by the symbol t, except in Table 1 where the full nomenclature t90/°C is used. The standard covers resistors or thermometers for all or part of the temperature range 200 °C to +850 °C with different tolerance classes, which may cover restricted temperature ranges. This second edition cancels and replaces the first edition published in 1983, amendment 1 (1986) and amendment 2 (1995). It constitutes a technical revision. The significant technical changes with respect to the previous edition are as follows: While the temperature/resistance relationship in 4.2 remains unchanged, there are several changes in the other chapters. Most important are: tolerance classes follow a new scheme; tolerance acceptance test is included; hysteresis test is included; several changes in the individual tests; appendices are deleted.