EPA is approving a revision to the Ohio oxides of nitrogen (NO<INF>X</INF>) State Implementation Plan (SIP) containing provisions which control emissions of NO<INF>X</INF> from large internal combustion (IC) engines, makes corrections to typographical errors in the previously approved Phase I NO<INF>X</INF> SIP, and expands the definition of NO<INF>X</INF> budget unit. This approval requires reductions in NO<INF>X</INF> emissions from large IC engines, based on cost-effective control measures. Large IC engines are defined in the State rule as emitting one ton or more of NO<INF>X</INF> per day during the ozone season. The Ohio NO<INF>X</INF> SIP Call IC engine inventory is based on the inventory of IC engines compiled by EPA as part of the NO<INF>X</INF> SIP Call rule. Including these engines in the Ohio plan reduces NO<INF>X</INF> to a level at which the State will meet its ozone season NO<INF>X</INF> budget. EPA is approving the State's revision because it satisfies the Federal requirements for Phase II sources and demonstrates that these rules will meet the Phase II budget for Ohio.