What does the IUPAC definition of the emf of a galvanic cell mean?

IUPAC's Gold Book defines the emf of a galvanic cell in the following way:

The limiting value of E(cell) for zero current flowing through the cell, all local charge transfer and chemical equilibria being established, was formerly called emf (electromotive force). The name electromotive force and the symbol emf are no longer recommended, since a potential difference is not a force.

I understand that zero current is required to find the emf since passing a current through the cell decreases its voltage. Moreover, we want to find the emf of the cell at some specific composition of the electrolytes, also ensuring a reversible reaction is taking place.

But what does it mean by "all local charge transfer and chemical equilibria being established"? Isn't the emf of the cell ZERO when the cell reaction attains equilibrium? What "equilibrium" does it refer to? And what does "local charge transfer" mean?

• Note that the Gold Book is only a collection of terminology from various other sources. Sometimes, you might find more information in the original sources (here: Green Book, 3rd ed., p. 71 and Pure Appl. Chem. 1996, 68 (4), 971). – Loong Jan 7 '17 at 12:42
• OK I'll take a look – Newton Jan 7 '17 at 15:24
• – Burak Ulgut Jan 10 '17 at 7:57

You are right that when the cell reaches equilibrium, the $E_{cell}$ would be zero. However, here we're interested in the equilibrium of each local process separately: eg. diffusion of ions from the bulk electrolyte to the surface will reach an equilibrium.