This standard establishes minimum safety and performance requirements for long-term electrocardiographic monitoring devices (ECGs), also commonly called ambulatory electrocardiographs (AECGs), that are intended for use in the analysis of rhythm and of relevant morphology of cardiac complexes. Subject to this standard are all parts of such devices necessary to: a) obtain a signal from the surface of a patient's body; b) amplify and transmit the signal to recording and display devices; c) record and display the signal; and d) provide summaries of rhythms, conduction disturbances, and displacements of the ST segment.