At the Center for Offsite Construction, some of our most important milestones arrive when two separate lines of research stop running in parallel and begin to strengthen one another. That happened again, this week.

Over the last months, the CfOC has been developing the CTO file type: a digital format meant to support a Configure-to-Order future in construction, where buildings are assembled from pre-designed, pre-engineered, and pre-certified products rather than redrawn from scratch on every project. At the same time, we have been leading the CfOC-ICC-1220 standards effort with the ICC, under our ANSI-accredited standards process, to define a repeatable interface between manufactured building products and the systems they connect to at installation.

Now those two projects have met. The result is the CIS file type: the CTO Interface Standard (specified inside the CTO file type standard).

This is a major step for the CfOC because it gives interface standards a proper digital home. The CTO file type was always meant to describe products and configurations in a Configure-to-Order marketplace. But as the work matured, it became clear that the interfaces between products deserved their own first-class format. A building product is one thing. The standard that governs how it mates to another product is another. Keeping those ideas separate is what allows both to become clearer, more durable, and more useful.

That separation addresses a big issue, that offsite construction has long struggled at the point of handoff from manufacturing. Many offsite products promise speed, precision, and predictability. Yet on real projects, uncertainty returns the moment two manufactured systems have to meet each other in the field. Whose geometry governs? Which side carries which service? What exactly counts as compatible? Too often, those questions are left to cut sheets, shop drawings, phone calls, and last-minute interpretation.

The CIS file type changes that. It prepares the had-off for automation – both for agents and blockchain.

A CIS file describes, in machine-readable form, the interface standard that two CTO manufactured building products use to connect. It defines the connection plane, the sides that approach that plane, the ports, tolerances, signatures, and requirements that make a valid connection possible. In simple terms, the CTO file can describe the products, while the CIS file can describe the handshake between them.

The release marks a conceptual advancement in the CfOC’s broader research agenda. The standards work and the digital file-type work are no longer merely adjacent. One is now helping structure the other.

This becomes especially important in the case of CfOC-ICC-1220. Until now, a standard like 1220 could be written as a conventional standards document and used by attentive humans. With the emergence of the CIS file type, that same standard can also be expressed as a machine-readable artifact. In other words, the logic of the standard can now travel directly into configurators, product catalogs, validation workflows, and other software systems that will be needed in a true CTO marketplace.

That shift means the work of standards can now become executable infrastructure.

It also means the CTO file type project has become more realistic, and interoperable for many actors. In earlier versions, too much interface logic had to live inside product definitions. That may work for a narrow or internal use case, but it is not a sound long-term structure for an interoperable marketplace. Standards bodies, manufacturers, software developers, and project teams all move at different speeds. A separate CIS format allows interface standards to evolve on their own cadence while products and assemblies continue to evolve on theirs. The result is a more modular digital ecosystem, which is exactly what a CTO marketplace requires.

This is also the kind of milestone that reminds us what the CfOC is trying to build. The CfOC admires other centers that publish essays, whitepapers, or policy. But we work every day to assemble the coordinated infrastructure of a new delivery model: standards, file formats, legal frameworks, educational pathways, and market logic that all support one another. Progress becomes especially significant when one piece of that system suddenly makes another piece stronger.

We celebrate that progress at this moment, when a standards-writing effort with ICC and ANSI buttresses a digital-specification effort that will soon also connect to the JDF. It is the moment when an interface standard becomes legible not only to human readers, but to software. And it is the moment when one of the CfOC’s central ideas becomes more tangible: the future of offsite construction will depend not only on better products, but on better interfaces between products, and on better systems for describing those interfaces clearly enough that the entire market can use them.

We are excited to share this milestone because it points toward a larger future. Configure-to-Order construction will require products that know what they are, files that know how those products are assembled, and standards that know how those products are allowed to meet. The CTO file type and the CTO Interface Standard are now beginning to divide that work properly.

For the technically interested, here is how you can read the specs:

- CTO File Format v0.2.0
- CIS File Format v0.1.3
- Example CIS file

About CfOC: The Center for Offsite Construction at NYIT's School of Architecture and Design researches the transition from Engineer-to-Order to Configure-to-Order workflows in U.S. construction. Learn more at centerforoffsiteconstruction.org.