It is not permissible to use abbreviations for unit symbols or unit names, such as sec (for either s or second), sq. mm (for either mm² or square millimetre), cc (for either cm³ or cubic centimetre), or mps (for either m/s or metre per second). 2025 August 14, “The International System of Units (SI)”, in Bureau International des Poids et Mesures, archived from the original on 17 Sep 2025, page 147: