[1] As a system of enzyme nomenclature, every EC number is associated with a recommended name for the corresponding enzyme-catalyzed reaction.
[2] Furthermore, through convergent evolution, completely different protein folds can catalyze an identical reaction (these are sometimes called non-homologous isofunctional enzymes)[3] and therefore would be assigned the same EC number.
The first version was published in 1961, and the Enzyme Commission was dissolved at that time, though its name lives on in the term EC Number.
Subsequent supplements have been published electronically, at the website of the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology.
[5] In August 2018, the IUBMB modified the system by adding the top-level EC 7 category containing translocases.