Workday Adaptive Planning supports exactly one top-level hierarchy structure per instance. The level hierarchy is a single-root tree structure, with 'Top Level' serving as the single apex node from which all organizational levels descend. This architectural constraint is by design: a single unified hierarchy ensures that rollup calculations, security access rules, and formula references operate consistently throughout the entire model. All company, department, cost center, and other organizational levels must be organized within this single hierarchy. While Adaptive Planning supports alternate reporting groupings through level attributes and dimensions, these do not constitute separate top-level hierarchy structures — they are metadata overlays on the primary hierarchy. Attempting to create multiple top-level roots is not supported in the standard configuration. Administrators must plan their level hierarchy carefully during implementation to accommodate all reporting and planning needs within this single-root constraint. Reference: Workday Adaptive Planning — Level Hierarchy Structure, Top Level Configuration, Implementation Best Practices.