This document specifies the common conventions required for the interchange of specific patient data (demographic, recording conditions ...), ECG signal data and metadata, ECG measurements and ECG annotations, and ECG interpretation results. This document specifies the content and structure of the information which is to be interchanged between digital ECG electrocardiographs/devices and computer ECG management systems, as well as other computer or information systems (cloud, etc.) where ECG data can be stored. This document defines the way to describe and encode standard and medium to long-term electrocardiogram waveforms measured in physiological laboratories, hospital wards, clinics and primary care medical check-ups, ambulatory and home care. It covers electrocardiograms such as 12-lead, 15-lead, 18-lead, Cabrera lead, Nehb lead, Frank lead, XYZ lead, Holter ECGs and exercise ECGs that are recorded, measured and analysed by equipment such as electrocardiographs, patient monitors, wearable devices. It also covers intracardiac electrograms recorded by implantable devices as well as the analysis results of ECG analysis and interpretation systems and software that are compatible with SCP-ECG. ECG waveforms and data that are not in the scope of this technical specification include real-time ECG waveform encoding and analysis used for physiological monitors, and intra-cardiac or extra cardiac ECG mapping.