Escutcheon is in Charges.
Escutcheon. Little shield. Sometimes used as a Difference when it is known as an inescutcheon.
Esme Stewart 1st Duke Lennox 1542 1583 Arms. Quartered 1&4 John Stewart of Darnley 1st Count Évreux 1380 1429 Arms, 2&3 Stewart Arms a Bordure Engrailed gules for difference, overall an inescutcheon of Lennox Arms the heiress of whom was Elizabeth Lennox Countess Évreux wife of John Stewart of Darnley 1st Count Évreux. Source.