Cadency

n. rhythm, measured movement; rise and fall of a voice (in speaking)

In heraldry, cadency is any systematic way of distinguishing similar coats of arms belonging to members of the same family. Cadency is necessary in heraldic systems in which a given design may be owned by only one person (or, in some cases, one man) at once. Because heraldic designs may be inherited, the arms of members of a family will usually be similar to the arms used by its oldest surviving member (called the "plain coat"). They are formed by adding marks called brisures, similar to charges but smaller. Brisures are generally exempt from the law of tincture.
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Noun
1. a recurrent rhythmical series
(synonym) cadence
(hypernym) rhythmicity

(n.)
Descent of related families; distinction between the members of a family according to their ages.
  

A mark of difference to show family relationships in the system of heraldry . Included in marks of Cadency are the label (1st son), crescent, mollet, martel, annulet, fleur-de-lis, rose, cross flory, octofoil.