Studio Arcanis

I've recently noticed that the Hexagram/Pentacle of Solomon utilized in the Heptameron and the Grimorium Verum are almost completely identical, also being generally similar to the Lemegeton Hexagram which only has a small change or two. I did some looking up online and True Grimoire and there seem to be no comments about the nature of these similarities, or even that the two are exactly the same! This was simply an observation I was hoping to perhaps start some discussion thereon. Perhaps those here who practice the Heptameron system or GV, or even better have experience with both, might know more about the symbolism and whatever practical differences there may be between them.

Also, does anyone know what the Greek inscription in the center of the hexagram actually means? From my parsing it seems to read Chrus, which seems to mean exactly nothing on the surface. Is it an acronym for something important in Christian mysticism of some sort? (Xpus is how the letters look in Latin).