The Level of Development (LOD) Specification provides guidelines for practitioners in the architecture, engineering, and construction industry to define the reliability and detail of Building Information Models (BIM) at various stages. The document aims to standardize communication regarding model deliverables, ensuring clarity between authors and users about what can be relied upon in a model. This specification, initiated by the BIMForum and influenced by AIA definitions, does not dictate specific project milestones but serves as a reference tool for defining BIM content.