What action creates an (Only) level?

In Workday Adaptive Planning, an (Only) level is automatically created when child levels are added beneath an existing parent level, converting it into a rollup. The (Only) designation refers to a system-generated virtual level that represents the data entered directly at the parent level, independent of its children's data. For example, when child accounts are created under 'Total Marketing,' the system creates a 'Total Marketing (Only)' level to capture any topside adjustments or entries made directly at the parent level. This prevents the double-counting of data that would occur if parent-level entries were included in child rollup totals. The (Only) level is not manually created — it is a structural byproduct of the rollup relationship. Planners who need to enter data at a rollup level must do so through the (Only) level, which requires specific permission settings in the user's permission set. Reference: Workday Adaptive Planning — Level Hierarchy, Rollup Levels, (Only) Level Behavior, Data Entry at Parent Levels.