What do the Johannesburg Heritage Foundation's 'ABC' ratings mean?

A = Outstanding heritage value. Don't touch our treasures.

B = Fine building. Beautiful and probably a good example of a period or the work of an excellent architect, with historical interest. It may also have landmark value. Touch with very great care, only after consultation and don't even think of demolition.

C = Good building, part of a significant group and probably contributes to street scene, but possibly only a façade. Don't touch without consulting the Johannesburg Heritage Foundation. Changes are possible but demolition will be resisted.