The Fact System provides a set of capabilities which standardizes and simplifies the creation of the QGC user interface.
A Fact represents a single value within the system.
There is FactMetaData associated with each fact. It provides details on the Fact in order to drive automatic user interface generation and validation.
A Fact Control is a Qml user interface control which connects to a Fact and it's FactMetaData to provide a control to the user to modify/display the value associated with the Fact.