In a Latimer diagram, the most highly oxidized form of the element is on the left side, with successively lower oxidation states to the right side. The species are connected by arrows, and the numerical value of the standard potential (in volts) for the reduction is written at each arrow. For example, for oxygen, the species would be in the order O (0), HO (–1), HO (-2):
The arrow between O and HO has a value +0.68 V over it, it indicates that the standard electrode potential for the reaction:
:O(g) + 2H + 2e ⇄ HO(aq)
is 0.68 volts.