The first hexagon is defined in the area where the X, Y and Z axes are all positive directions.

As shown in the figure

In space solid geometry, the whole space is divided into eight parts by mutually perpendicular coordinate axes X axis, Y axis and Z axis, and each part is called an octant circle.

Eight diagrams are usually marked by Roman numerals "one, two, three, four, five, six, seven and eight" in geometric figures. The most common numerical order of divination limit is that the divination limit determined by X-axis positive semi-axis, Y-axis positive semi-axis and Z-axis positive semi-axis is "the first divination limit", and the Roman numeral is marked as "I". The numerical order of the second, third and fourth hexagrams is similar to that of quadrants in plane rectangular coordinates. Increase the numbering order counterclockwise on the xy plane. Then the fifth to seventh hexagrams are also marked counterclockwise on the xy plane.

reference data

Baidu Encyclopedia:/item/%E5% 8d% A6% E9% 99% 90/1021722? Fr = Aladdin