Users also have tacked non-standard divisions, such as Division 17, on to the 1995 edition's 16 divisions. Officially, there is no such thing as Division 17, but many different versions of it have been created in organizations across the country. They cover everything from telecommunications to railway track work to traffic signaling devices. The evolution of Division 17 reflects the inability of some users to properly determine subject matter locations, or to find a location that suited what they were attempting to specify.

Even with a Band-Aid like Division 17, critical project information could be misplaced or left out entirely, resulting in costly and time-consuming change orders, errors, and omissions. The inconsistent use of non-standard MasterFormat numbers for subjects not covered by the 16-division structure diminishes construction coordination, and users of construction documents pay for the inconsistencies in time spent searching for information, or the consequences of overlooking information that is improperly located. The old 16-division format, designed for buildings 40 years ago, also proved to be inadequate for horizontal construction work and the complex process engineering construction of today. Consequently, the 2004 Edition has expanded the existing 16-structure division and provided specification locations for categories not offered before, such as heavy civil engineering projects (roads, bridges, tunnels, utilities, etc.), and industrial construction (factories and power plants).