UEFI-based platform boot

https://depletionmode.com/uefi-boot.html

Quote

SEC Genesis 1
1 In the beginning, the firmware was created.
3 And the Power Management Controller said, Let there be light: and there was light.
2 And while it was with form, darkness was indeed upon the face of the deep.
  And the spirit of the BIOS moved upon the face of the flash memory.
4 And SEC saw the light, that it was good: and proceeded to boot.

Platform Initialization starts at power-on. The first phase in the process is called the SEC (Security) phase.