5. How do the various elements of an emergency plan fit together?

The ORSEC system is made up of modular elements, which take into account the need to adapt the response to requirements, whether in terms of the resources deployed, the direction of operations, and so on.

Example: if the disaster is contained within your site, you will decide on all emergency measures, including calling in the external emergency services. Once the external emergency services are on site, you'll be in contact with their commanding officer, and you'll be their point of contact. This means that you play the role of internal DOS (Director of Emergency Operations).