After applying the control factors to the SMOKE intermediate inventory file, the Grwinven program writes a new SMOKE intermediate inventory file that contains the new, controlled emissions. Grwinven writes only the I/O API part of the inventory and not the ASCII part, because the ASCII part that contains the state/county codes, SCCs, and other character strings does not change between the base and future or past year. All of the sources in the base and controlled inventory files are the same; the difference is in their emissions values.

Grwinven can also output the ORL inventory format (in addition to I/O API format), which is also a SMOKE input format.