The Stratification Method for the Best Arrow Line Net Drawing in the Shape of the Tree

Based on the working procedure table,this paper analyses all t he working procedure,presenting the logical relationship among the working proce dures in the form of the working procedure tree.Again,this paper uses the means of the working procedure tree to precisely indicate the position and direction of the suppositional working procedure ,putting forward the stratification metho d for the best arrow line net drawing in the shape of the tree.