Techniques for using billing services to manage a personal address book are provided. An upper region of the stem can have one or more of its layers folded to increase suspension wire breakout strength. Using the aforesaid structure, false-welding and accompanied shortcomings as disengagement of the core terminal, and poor contact and conductivity are prevented, while accomplishing objects as economizing materials and lowering production costs. Therefore, a system 1 is suggested which comprises a probe holder 2 to which a probe 4 is rigidly attachable. A mode setting push-button switch 113 is operated to turn the indication indicating a set pressure displayed by a display unit 116 through an angle of 180\xb0, a function to increase the set pressure of a first push-button switch 111 is reversed and a function to decrease the set pressure of the second push-button switch 112 is reversed. The candidate virtual nodes may be analyzed according to a selection criteria and a virtual node may be selected.