The drawings indicate that "the building is 0.000, which is equivalent to the elevation of 2.3m in the Yellow Sea". How to determine the height of this building with plus or minus 0.000? (Jiangsu area) The altitude of the Yellow Sea is not suitable, so it should generally be called the altitude of the Yellow Sea. For the altitude of the Yellow Sea, the landlord can refer to:

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Every city has many elevation points (BM), and the surveying and mapping department has comprehensive data. When setting out the project, let them find an elevation point nearby, and according to the height of this point, they can survey the plus or minus 0.000 of the project.