What is Line?

A single line in a hexagram. A solid line (—) is yang; a broken line (– –) is yin. Lines are numbered 1 to 6 from bottom to top. Each line carries its own text in the I-Ching and, in Liu Yao analysis, receives a stem-branch assignment, a five element attribute, and a six relative classification.

Source: Xi Ci Zhuan (繫辭傳): "The yao emulate the movements of the world"