R is for right, and is commonly used in imaging reports and electrocardiograms. R is short for right, and L is short for left. To differentiate between right and left in an imaging report, an R or L is added to the film or to the imaging report to avoid confusion. In the ECG examination, it is also necessary to distinguish between the electrodes of the right and left upper limbs and the right and left lower limbs, in which the electrodes of the right upper limb are red R, the electrodes of the left upper limb are yellow L, the electrodes of the right lower limb are black R, and the electrodes of the left lower limb are blue gray L. Failure to distinguish the position correctly will affect the diagnosis of the disease as well as subsequent treatment, so it must be disposed of in strict accordance with the norms.