The pattern found in the Tzolkin of the black squares is called the Loom of Maya. These days are known as days on which galactic activation portals or "portal days" happen. In the center of the Loom, there is a whole column in which no portal days happen. This is called the "Mystic Column", and in a way represents the YAXCHE or "Green Tree" which is equatable to the Sacred Tree of Life, in a way, the tree from which life springs forth into this world.