and the signs of the banners
Just a short list I made from the top of my head. Please share any criticism, obvious mistakes I made and ideas.
*) The source of the translations of the names isn't from MS, so take them with a grain of salt. They do seem to fit though.
North:
Black: alchemical meaning: The Blackening, first matter, chaos.
OIP TEAA PDOCE, He Whose Name Is Unchanged From What It Was. May refer to the First Matter.
The symbol of the banner is the alchemical symbol of Life Force, Health. The ankh is also used as a symbol to mean the same thing.
West:
Green, alchemical meaning: taming of raw natural forces
MPH ARSL GAIOL, He Who Is the First True Creator, the Horned One
May refer to the symbol of Mercury. Mercury, the roman god, is also usually depicted standing with a ram. Aries is also used to refer to the phase of Calcination.
The symbol on the banner is from the Ensign of Mercury
South:
White: alchemical meaning: Purification, the White Stone, feminine
MOR DIAL HCTGA, He Who Burns Up Iniquity Without Equal (Clear reference to the purification phase)
The symbol on the banner is used for White Lead in alchemy, which is a byproduct of dissolving lead with vinegar. Possibly to remove it from gold and other precious metals. White lead was commonly used as a coloring agent in paints. The metal tin is was also called white lead (plumbum album) by the romans.
East:
Red: alchemical meaning: the Red Stone, completed Great Work, masculine
ORO IBAH AOZPI, He Who Cries Aloud In the Place of Desolation
May refer to the finding of ones Higher Identity. To quote the spiritual alchemist Rumi: “In the driest white stretch of pains infinite desert, I lost my sanity and found this rose”. May also be a reference to the Philosophers Stone, the purest form of matter, the unified theory of everything, etc.
The Tau Cross was used as a "Sign of the Elect" in the Old Testament, being traced on the heads of the initiates by the Angel of Yahweh.