To this end, let us try to uncover a possible origin of the generally confusing state of affairs. We can conveniently begin by reviewing a classic paper by Cha , where the mechanism selection Eqns (2)-(3) were first derived, alongside the newly derived Eqn (1). In a section of the paper entitled Determination of k obs and differentiation of mechanism, Cha lists Eqns (2)-(3) in his Table 1 on p. 2182 of the paper, and associates those two equations with Mechanism A and B, respectively. Then the author issues a crucially important caveat: "It must be pointed out that the significance of k obs [...] holds true only when the depletion of free inhibitor by binding is negligible. Therefore, for this approach to be valid, the enzyme concentration must be an order of magnitude or more lower than the inhibitor concentration", meaning lower than even the lowest inhibitor concentration utilized in the inhibition assay. One major source confusion stems from the fact that Cha's paper happens to be entitled "Tight binding inhibitors: I. Kinetic behavior". It is probably somewhat easy to lose track of the fact that many results presented in Cha's 1975 paper do not actually apply to the tight-binding situation.