|Definition:|| quantity, defined by a conventional measurement procedure, for which a total ordering relation can be established, according to magnitude, with other quantities of the same kind, but for which no algebraic operations among those quantities exist
NOTE 1 – Ordinal quantities can enter into empirical relations only and have neither units of measurement nor dimension. Differences and ratios of ordinal quantities have no physical meaning.
NOTE 2 – Ordinal quantities are arranged according to ordinal value scales.
NOTE 3 – Examples: Rockwell C hardness, octane number for petroleum fuel, earthquake strength on the Richter scale, subjective level of abdominal pain on a scale from zero to five.