One might assume that these notations are equivalent, but are they really? Please note that I am not referring to the use of dashes, parentheses, or brackets to separate the unit, but rather to what these notations represent. In a reasonable understanding, example (i) suggests that everything to the left of the parentheses is related to the reference, i.e. that the potential "E" in volts "V" is represented on the REF. Examples (ii) and (iii) explicitly differentiate between the potential or the unit being represented on the REF, respectively. A fair argument in favor of example (ii) could be that it is the potential that is measured in relation to the REF, not the unit itself. However, when considering practical examples involving the reversible or standard hydrogen electrode, denoted as RHE and SHE, respectively, the notation becomes somewhat awkward when numerical values are involved, e.g. "0.5 vs. RHE V", and is rarely encountered in the literature. On the other hand, placing the REF at the end of the notation (with or without parentheses) is the most conventional way of representing reaction potentials in textbooks and is also common when numerical values are used in the text, e.g. "0.5 V vs. RHE". The latter format is often employed in the text even when the author(s) utilize a different notation in figures (see Ref. as an example).