Grass Valley GV STRATUS v.3.1 - Manual (Page 235)

Select Edit | User Preferences | ALP and check the Allow Placeholder Deletion box.
Adding a new sequence
You can add a new sequence to a placeholder in the Assignment List tool.
1. Select a placeholder that you want to add a new sequence into.
2014 02 21 GV STRATUS User Manual 235
Using the Assignment List