The typical sequence of steps in utilizing the cad software consist of the user selecting the function to be performed, and the particular way it’s to be operated (usually the system offers several different ways to accomplish a given task, as for example a circle can be built by specifying it’s center and radius or alternatively by entering three points), to enter the necessary information (via supplying the coordinates of end points for the line), and then for the program to apply this function using data provided by the user of 3d cad software. When a particular entity or selection set of entities are to be modified, the user must apply some selection method to specify desired objects.