Details about the sequence are entered in the area "Title or author / editor changes".
To enter a preceding exsiccatal series, click on the button. This will open a form where you can search for an exsiccatal series. If you want to remove the relation to a preceding exsiccatal series, click on the button. To change to a different exsiccatal series shown in the hierarchy, select it and click on the button.
If there happens to be a loop or a selfreference in the sequence the client will show you this by highlighting the hierarchy as shown below.
The button will be activated. You can change to the exsiccatal series that should be to topmost one in a sequence by using the button. Than click the button to remove the reference to the precessor of this series.