The Predecessor / Successor Editor gives you a convenient place to manage all of the relationships that are the heart of your schedule. These windows show all predecessors and/or successors of the selected activity, as well as the type of relationship, starts and finishes, lags, and whether a relationship is driving the successor of that relationship. The lag and relationship type can be edited from this window by double-clicking the cell you would like to edit, and making the change. Relationships can be deleted by selecting the predecessor or successor in the list, and clicking the "Delete" button. The "Lag To" button gives you the ability to select a date the successor should start or finish on (depending on relationship type), and Phoenix will calculate the amount of lag necessary to make the activity land on that date (taking non-work calendar days into account) and save it off in the relationship.