What do Shaoyin, Shaoyang, Taiyin and Taiyang mean in the Book of Changes?

"Tao is tai chi. Taiji gives birth to two instruments, which are divided into four images and four images are divided into eight diagrams. " The lunar sun belongs to the second of the four elephants, and (the four elephants are divided into lunar, shaoyin, sun and shaoyang). The second instrument is the basic unit of gossip, which is yin, one long horizontal (not easy to draw) is yang, and the other is yang.