"Cadency" is the technical term for differencing, i.e. personalising, arms to identify individual members of a family. It isn't enforced in South Africa, and the Heraldry Act confirms that it's optional when matriculating arms at the Bureau of Heraldry (though it doesn't state whether the option rests with the armiger or with the Bureau).

Several methods are used in South Africa: adding a brisure, adding a bordure, changing tinctures, substituting charges, varying a line of partition, and varying the number of charges. In some families, more than one method is used.

Adding a Brisure
A "brisure" is a charge that is added to the arms to identify a specific person. In England, it's often called a "mark of cadency", and the system which has been in use there for the past 500 years or so assigns specific marks to specific male members of the family: a 3-pointed label for the eldest son (during the father's lifetime), a crescent for the second, a mullet for the third, and so on. It's not a very practical system, and its use there has long since become a matter of courtesy.

No doubt, many English South African families have used this system, and there are a few examples of it among the arms matriculated at the Bureau, e.g. those in the Brownell family.

The English system doesn't provide for daughters because, in English law, there is no difference in their seniority. In 1999, Canada introduced a set of marks of cadency for daughters, including a heart for the eldest, an ermine spot for the second, and a snowflake for the third.

In South Africa, various charges have been used as marks of cadency for daughters, and one family (Welgemoed) is reported to have used the Canadian system. Charges which have been used as brisures in South Africa (for sons, as well as daughters) include a triquetra (Brownell), a sun in splendour (Fourie), an eagle and a cross botonny (Gast), and an ox-yoke (Hiemstra).

Adding brisures is also the principal method used to difference a family association's arms for an individual member of the family, and association arms registered at the Bureau always have a blank chief for that purpose. An example is the arms of the Scheffer Family League (BoH 1992), which were differenced for Hercules Scheffer by adding two powder-horns, and changing the lower line of the chief.

Adding a Bordure
Scotland uses a system of cadency, known as the Stodart System, based on adding bordures to the paternal arms. It is quite complicated, and the Lord Lyon determines the appropriate differencing for each "cadet", i.e. member of the family.

Among the arms matriculated at the Bureau are those of the Rains family which has used this system, with a label for the eldest son (during the father's lifetime), a red bordure for the second, and a gold bordure for the third.

Bordures have also been used in a few other families, but not according to the Stodart System.

Changing Tinctures
Arms can be differenced by changing one or more of the tinctures.

This method was used to personalise the historical Schlebusch arms (in silver, black and gold) for Alwyn Schlebusch (gold, black and red) (BoH 1971).

Examples are to be found in the Gast family, where the third and fourth sons' arms have different tinctures to those of their elder brothers and father:

Substituting Charges
Another method of differencing is to replace a charge in the existing arms with some other charge.

For example, two men named Schwartz registered similar arms, one with a lion in chief and the other an eagle. Two De Klerk brothers have identical arms, except that one has a coronet in the centre and the other has a lymphad.

In the Gast family, referred to above, the children of the third son replace the black botonny cross with other charges (a gryphon, a baobab tree, and an owl respectively), with the result that their arms bear no obvious family resemblance to each other or to their father's, uncles', cousins', grandfather's arms (BoH 2005).

Perhaps the most extensive use of this method is to be found in a branch of the Linde family, where the arms have been matriculated through two generations by varying the charges on the chief:

Substitution of charges is widely used as a method of differencing in Army unit arms. It was also used in the arms of the various departments of the former House of Assembly.

Varying a Line of Partition
Arms can be differenced by altering lines of partition. This forms part of the Stodart System in Scotland, and also stands alone. The arms of the Hiemstra brothers (BoH 1974), for instance, include an embattled chief, the one brother's chief having six crenellations and the other's five.

In the arms of three members of the Bütow family (whose relationship to each other isn't stated), the lower edge of the chief is respectively indented, wavy, and engrailed (BoH 2000). The arms with the indented line have been matriculated for the armiger's daughter, with the addition of a bordure.

Varying the Number of Charges
Sometimes, the design of a coat of arms lends itself to differencing by increasing or decreasing the number of repeated charges. The only South African example I've come across is the arms of Carl van der Merwe (BoH 1972), derived from those of the Dutch noble family Van der Merwede (arms which are reportedly borne by many Van der Merwes even though no blood or DNA relationship has been proved). The number of bezants in the arms was reduced from fifteen to six.

Combination of Methods
Some families do not confine themselves to a single method. The arms in the Gast family, referred to above, are perhaps the most varied example. The eldest son has a label, his son has a 5-pointed label, and each daughter has a small cross as a mark of cadency. The second son added an eagle as a mark of cadency, and his son has a label as well. The third son changed tinctures and his children replaced the cross with other charges. The fourth son also changed tinctures.

References/Sources/Links

South African Heraldry Website © Arthur Radburn