The Extends metric is used to get information about how many interfaces are extended by a function block or an interface.
A function block can extend exactly one function block and implement multiple interfaces. An interface can extend multiple interfaces, but cannot implement other interfaces.
A function block or an interface can extend none or several interfaces. The number of direct extended interfaces is counted.
Example
Extends calculation example:
FB_Test extends FB_Base implements IF_Test1, IF_Test2
FB_Base implements IF_Test4
IF_Test2 extends IF_Test3, IF_Test5
Implemented By Results
Extends (FB_Test) = 1
Extends (IF_Test2) = 2