What are the carving methods for stone carving?

Line carving, as an ancient carving technique, was first embarked upon in stone, wood, metal, and hard objects such as shells and ceramics, where simple graphic shapes were carved by means of lines. When carving the Nine Dragons Wall, it is usually used to show the general outline of the nine dragons, as well as being used in detailed carvings. Line carving can be divided into two types of carving, one is "negative line carving", that is, through the form of concave lines to express the image of the carving; the other is "positive line carving", is the use of convex lines to show the image. In the nine dragon wall carving, according to the different parts of the dragon, need to be flexible and skillful use of these two ways, show the dragon's basic body shape, is the basic use of other carving methods.