On: The examples in the textbooks are not representati...

[exmadscientist]

They're not far off, especially near the triple point of water: https://www.bipm.org/documents/20126/2619564/Estimates_Diffe...

See also section 2 of the more-or-less authoritative parent document "Mise en pratique for the definition of the kelvin in the SI", available at https://www.bipm.org/documents/20126/41489682/SI-App2-kelvin...