Are organizations required to use National Incident Management System (NIMS) as an incident command structure?

Any examples are for illustrative purposes only.  

The Joint Commission has no standard that specifically addresses educational requirements or type of incident command structure.  Some choose to use the National Incident Management System (NIMS) as an incident command structure. If the organization is required to use NIMS by their state or local controlling authority, then per standard LD.04.01.01, the requirements of that controlling authority with regard to NIMS implementation and educational requirements must be followed. 

The Joint Commission has no standard that requires the organization's staff to receive formalized training with regard to incident command structure. EM.01.01.01 EP 7 requires that the hospital's incident command structure be integrated into and consistent with its community command structure. As a result, the community's emergency management authority may require or recommend specific training. Staff are to be trained to be competent to effectively accomplish their assigned duties. 

Reference EM.01.01.01