1.1 ,This practice may be used for measuring, scoring, and improving the overall performance of detectors that alarm on traces of explosives on swabs. These explosive trace detectors (ETDs) may be based on, but are not limited to, chemical detection technologies such as ion mobility spectrometry (IMS) and mass spectrometry (MS). Technologies that use thermodynamic or optical detection are not specifically addressed, but may be adapted into future versions of this practice.