Emergency Alert System code of regulations, if anyone else wants to dig
https://www.ecfr.gov/cgi-bin/text-idx?SID=49b5be2a4c88007790b0526af7036b54&mc=true&tpl=/ecfrbrowse/Title47/47cfr11_main_02.tpl
found this bit interesting:
§11.54 EAS operation during a National Level emergency.
(c) During a national level EAS emergency, EAS Participants may transmit in lieu of the EAS audio feed an audio feed of the President's voice message from an alternative source, such as a broadcast network audio feed.