CLASS class_name "description" EXTENDS ext_type_or_class_name WITH [object_assignment];
"class_name" is the name of the class
"description" is a string expression
"ext_type_or_class_name" is the name of the class or type used to extend from
"object_assignment" is the object assignment the class is extended with
When a class extends another class it means that the extension is concatenated with the objects of the original class. This can also be done recursively.
Example:
CLASS Flow EXTENDS Sensor WITH {: Comments <- "A model for a sensor measuring the flow rate"; Equations <- { interface.y_M = state.Q_In; }; :};