Notification: Free Reference Object (BADI)

Hi All,

When we define Screen areas in Notification Header for any notification type, in Screen Type Object drop down there option O550 Object: Free Reference Object (BADI).

Can anyone tell:

1. What is the meaning of it

2. Does this changes the options in Screen Structure in Extended View (while defining the screen areas)

3. 'Free reference means, can we define our own fields in this

Your answer will be really helpful.