From the wiki page, what I understand is
an Area Control Center (ACC), also known as a Center (or in some cases, en-route, as opposed to TRACON control), is a facility responsible for controlling aircraft en route in a particular volume of airspace (a Flight Information Region). In the United States, such a Center is referred to as an Air Route Traffic Control Center (ARTCC).
My question: Is ARTCC code different from the ICAO-FIR code? Or are there anomalies?
For example, here's a NOTAM in the FAA site. AT the bottom, under the headline Other Information, the ARTCC code is given as ZDC. Can I safely assume that the ICAO-FIR code would be KZDC for that NOTAM?