This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
A hexagram line is the atlas's entry for one of the six stacked positions that make up a single hexagram in the I Ching, the ancient Chinese divination text often called the Book of Changes. Each hexagram is built from six horizontal lines read from the bottom upward, and every line is either broken, called yin, or unbroken, called yang, so one entry here records a single position, which form it takes at that spot, and the traditional judgment text attached to it.
A line's traditional meaning depends heavily on where it sits in the stack, not only on whether it is broken or unbroken. The same broken line near the bottom of a hexagram commonly carries a different reading from an identical broken line at the top, since the six positions are conventionally read as a loose progression from a situation just beginning at the base to one already passing at the summit, and an entry records that positional sense alongside the line's own judgment.
A changing line, one singled out in a given reading as unstable, is what turns one hexagram into a second, related hexagram, and it is usually the line a diviner is told to weigh most carefully. The atlas records each line as its own distinct entry because a hexagram's overall reading and any one line's own judgment text are two connected but separate layers of the same passage, not one standing in for the other.