The sixty-four gates of Human Design map one-to-one onto the sixty-four hexagrams of the I Ching, each placed at a fixed position on one of the nine centres of the bodygraph. When the Sun, Moon, planets or nodes activate a gate at the moment of birth (and at the "design" moment some three months before), that gate is switched on, and pairs of activated gates form the channels.
Each gate carries a keynote derived from, but not identical to, the meaning of its corresponding I Ching hexagram, and the sixty-four gates distributed across the centres are the most detailed layer of the Human Design chart.