Doubt regarding setproperties() method and set.propertyname method in system objects block in Simulink.

While associating a system object file with a Simulink system block I have observed 2 things: 1. The constructor method of the system object class contains setproperties() method with vargin. 2. Also set.property_name methods are written for various properties.

For which properties do we call these separate methods? Is it that the set.property_name methods get automatically called during run time and are used to set values to properties visible in the dialogue box created for the system block? Also as far as I know, the setupimpl() is called first when we run our model. So what is the job of the constructor?