This document defines the application of medical waveform format encoding rules (MFER) to describe long-term electrocardiography waveforms measured in physiological laboratories and health care clinics. It covers electrocardiography such as bipolar 2, 3-lead, 12-lead that are measured by medical equipment such as Holter electrocardiograph and patient physiological monitors that are compatible with MFER documents encoding rules (see ISO 22077-1).