A method for service protection switching in a connectionless network is provided. In one such method, a pulsed ultraviolet radiation source for producing ultraviolet lithography radiation having a wavelength shorter than about 300 nm at a fluence of less than 10 mJcm2pulse and a high purity fused silica lithography glass having a concentration of molecular hydrogen of between about 0. In the back door structure a fit posture of the back door is corrected due to a vertical position of a mounting surface of the door hinge at the right side being set at an upper side with respect to a mounting surface of the door hinge at a left side in a state of not supporting the back door.