This design found it's origin in the tradition of distinguishing Christ within icons using the cruciform halo. When you see Christ in an icon you will notice three greek characters in every icon dating back to around the 11th century. These characters translate to I AM in reference to EX 3:14. That is why you will also see within this design the "EX" on the top left, and the "3" and "14" on the bottom right.
At the very bottom of the design there are three outlined strokes surrounding one filled in stroke. This represents the Trinity.
I have placed an image of the icon I referenced below.
-Peter
