What is a Grand Complication?

To start, it is a good idea to understand what a complication is (hyperlink). From there we can start to determine what a grand complication can be. Most agree that a minute repeater, perpetual calendar, moon phases, grand and petite sonnerie, and split-seconds chronograph make up a grand complication. The idea that the complication is grand comes from the fact that it is notoriously difficult to develop.