E and M lead signaling

E and M lead signaling

[¦ē ən ¦em ′lēd ‚sig·nəl·iŋ]
(communications)
Communications between a trunk circuit and a separate signaling unit over two leads: an M lead that transmits battery or ground signals to the signaling equipment, and an E lead which receives open or ground signals from the signaling unit.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.