 A report published in 2007 by the Consultative Committee for Thermometry to the CIPM noted that their definition of temperature had proved to be unsatisfactory for temperatures below 20 K and for temperatures above 1300 K. The committee was of the view that the Boltzmann constant provided a better basis for temperature measurement than did the triple point of water, as it overcame these difficulties.Over the next few years the support for natural constants grew and details were clarified, until in November 2018, the 26th General Conference on Weights and Measures voted unanimously in favour of revised definitions of the SI base units.The 2019 redefinition of the SI base units came into force on the 144th anniversary of the Convention, 20 May 2019.