salt form of an ion exchanger

https://doi.org/10.1351/goldbook.S05449
The ionic form of an @[email protected] in which the @[email protected] are neither hydrogen nor hydroxide ions. When only one @[email protected] is possible for the counter-ion, or its exact form or charge is not known, the symbol or the name of the counter-ion without charge is used, e.g. sodium-form or Na-form, tetramethylammonium-form, orthophosphate-form. When one of two or more possible forms is exclusively present, the @[email protected] may be indicated by a Roman numeral, e.g. FeII form, FeIII form.
Source:
PAC, 1993, 65, 819. (Nomenclature for chromatography (IUPAC Recommendations 1993)) on page 855 [Terms] [Paper]