In the archives of Saint-Lô exists a charter, dating from the First Crusade, on which is found the seal of Renaud de Carteret.
This seal shows that, during the latter part of the twelfth century, the de Carterets discarded their non-heraldic "equestrian" seal, and took into use the following arms: Blazon of Gules, en Fess Three Fusier Argent, Etiqueter Azure.
(Red Shield, a Horizontal Stripe with Three Silver Lozenges (fusils) with a Blue Label).
The Etiqueter Azure, or blue label, is a device of cadency (brisure) used by a first son.
A label is removed on the death of the father, and the son inherits the plain coat.