cadency

Cadency in heraldry refers to the system of marking variations in a family's coat of arms to distinguish different family members, particularly younger sons, from the head of the family. These marks, known as cadency marks, were used to show a person's position within the family structure, reserving the full, undifferenced arms for the family head.1

Historically, specific marks like a label, crescent, or mullet were assigned to indicate birth order. However, these strict rules have largely fallen out of use in many places, with most family members using the full arms. Exceptions exist, notably within the British royal family, where a strict cadency system is maintained due to the sovereign nature of the royal arms. In Scotland, cadency is precisely regulated, reflecting the clan system, where only the chief can bear the undifferenced arms, and others must petition for variations.1