Fimbriation
In heraldry and vexillology, fimbriation refers to small strips of colour placed around heraldic charges or ordinaries in order for them to stand out from the background.
According to the rules of heraldic blazonry, two areas of colour may not be placed next to each other, and nor may two areas of metal (in heraldry, "metal" refers to gold and silver, and their colour analogues, yellow and white. "Colour" refers to all other colours). In order to get around the occasional necessity of having two colours or two metals close together, fimbriation is placed between them.
South_africa_flag_large.png
In modern vexillology, the rules of heraldry do not strictly apply, yet fimbriation is still seen. A good example of a flag which uses fimbriation is the national flag of South Africa which is fimbriated in white above and below the central green area, and in yellow between it ant the triangle at the hoist.