ISO 16773-4:2017 gives some typical examples of impedance spectra of polymer-coated and uncoated specimens (see Annex A). Some guidance on interpretation of such spectra is also given. Further examples of spectra of low-impedance systems (range from, e.g. 10 Î© to 1 000 Î©) are given in ISO/TR 16208 and in ASTM G106. ISO 16773â€‘2 gives guidelines for optimizing the collection of EIS data with focus on high-impedance systems.