Sign refers to the poem corresponding to the sign drawn by lot, which is used to explain the meaning of sign.
Second, what is hexagrams?
Guaxiang generally refers to 8864 hexagrams, with 384 hexagrams. These hexagrams have corresponding explanations, called conjunctions, and those who explain conjunctions are called haiku.
If the constellation does not match the hexagram, which one shall prevail?
Not necessarily. It depends on what you measure or what method you use, and you need a professional to answer it on the spot, or you can judge for yourself which is closer to the truth.