Defines the general requirements for the oxygen index (OI) test which are further described in ISO 4589-2 and ISO 4589-3 as follows: - ISO 4589-2 defines a method for determining the minimum volume fraction of oxygen in a mixture of oxygen and nitrogen introduced at 23 Degree C +/- 2 Degree C that will just support combustion of a material under specified test conditions; - ISO 4589-3 defines methods of carrying out the same determination over a range of temperatures typically between 25 Degree C and 150 Degree C (although temperatures up to 400 Degree C can be used).