Abbreviation for standard temperature (\(273.15\ \rm{K}\) or \(0\ ^{\,\unicode{x26ac}}\rm{C}\)) and pressure (\(10^{5}\ \rm{Pa}\)); usually employed in reporting gas volumes. Note that flow meters calibrated in standard gas volumes per unit time often refer to volumes at \(25\ ^{\,\unicode{x26ac}}\rm{C}\), not \(0\ ^{\,\unicode{x26ac}}\rm{C}\).