IOF
The IOF is the first facility from which the IMAT manages incident-level operations. It is a temporary facility until a more suitable facility is secured for the JFO.
JFO

The JFO is the primary Federal incident management field structure. The JFO is a temporary Federal facility that provides a central location for the coordination of Federal, State, tribal, and local governments and private-sector and nongovernmental organizations with primary responsibility for response and recovery.

The JFO structure is organized, staffed, and managed in a manner consistent with the principles of NIMS. Although the JFO uses an ICS structure, the JFO does not manage on-scene operations. Instead, the JFO focuses on providing support to on-scene efforts and conducting broader support operations that may extend beyond the incident site.

IMAT
FEMA has both Regional and National IMATs that stand ready to deploy in response to an incident. If the magnitude and severity warrant the deployment of multiple IMATs, those IMATs join into one IMAT for the JFO.
FCO
The FCO is the individual, appointed by the President and deployed by the RA, who is responsible for the overall management of the Federal response, short and intermediate recovery, and mitigation activities for the incident. The FEMA RA(s) delegates authority and Disaster Recovery Manager (DRM) responsibilities to the FCO during an incident, and the FCO has directive authority over all Federal resources assigned to the incident management organization.