Why are certain divisions (such as 15 to 20) not assigned in MasterFormat 2014?

In MasterFormat 2014, certain divisions, such as those numbered 15 to 20, have intentionally not been assigned to provide flexibility for future expansion. This unassigned numbering allows for the potential inclusion of new divisions or categories to adapt to emerging industries, practices, or technologies that may develop over time. By leaving these divisions open, MasterFormat can update and evolve without needing significant restructuring, ensuring that it remains relevant in a rapidly changing construction landscape. This foresight supports the long-term utility of the MasterFormat system, making it suitable for diverse projects and innovations that may occur in the future.