Empty lines are generally the concept of flying stars. If you just sit at the junction of two mountains, it is vanity. If there is divination, that is, empty death between the eight houses, it is a big empty death, which is usually an unusable geomantic omen. Some schools think it is a house of great evil. This boundary, defined by some schools, refers to the position of 1.5 (total * * * 3) around the boundary.
Others regard the sitting posture that needs to be replaced by stars as a small empty death. Most compasses have 120 points, each of the 24 mountains has 5 points, and each mountain has 15, with 3 points. If the vertical direction is in the middle of each mountain, that is, within 9 degrees, take the hexagrams under the stars. If it is within 3 degrees of the side of each mountain, it is in two directions. Sitting in the same direction, if there is divination or yin and yang, you must use stars to divine. When it is necessary to substitute divination, some people think it is a small empty death.
Some factions don't use these lines because the earth's magnetic field is not a single point, and it deviates every year. If we divide the degrees of the compass so finely, it seems that the fire pit line of the big hexagram doesn't even have one degree, then there is a great chance of deviation. A ghost house might be better. Yang's house usually has a great influence on electromagnetic radiation in the city. The elevator in front of the door is enough to make your compass deviate from one or two mountains, so it is impossible to measure it so carefully. Therefore, the big hexagrams are generally used in the yin house, and the flying stars are used in both the yin house and the yang house. The double substitution of flying stars in Yangzhai depends on Feng Shui schools, some schools use it and some don't.
Xing Fei's jewelry line and fire pit line are actually not the same line, but refer to the mountain direction and the mountain launch bureau. Wang Ding Wang Cai is a jewelry line, and the loss of money is a fire pit line.
You have to have a certain foundation to ask such a question, so some basic terms will not be explained in detail. For example, twenty-four mountains, sharing gold, etc. After all, it takes more than a few words to explain these words.