IEC 60539-2:2019 is available as IEC 60539-2:2019 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.

IEC 60539-2:2019 is applicable to surface mount directly heated negative temperature coefficient thermistors, typically made from transition metal oxide materials with semiconducting properties. These thermistors have metallized connecting pads or soldering strips and are intended to be mounted directly on to substrates for hybrid circuits or on to printed boards.
This edition includes the following significant technical changes with respect to the previous edition:
a) revision for the structure in accordance with ISO/IEC Directives, Part 2:2016 (seventh edition) to the extent practicable, and for harmonizing with IEC 60539-1:2016;
b) the upper category temperatures of 175 °C, 200 °C, 250 °C, 315 °C, 400 °C in Table 1 have been added;
c) the dimensions of 0402M in Annex A have been added.