A release layer paste used for producing a multilayer type electronic device and forming a release layer of a thickness of 0. A method for prediction of onset of labor comprises applying the electrodes to an abdominal andor vaginal surface of a subject, collecting and analyzing the data, and displaying the result in terms of one of a small number of discrete results indicative of the state of preparedness for labor. A strap is attached to the heel end of the sole plate and extends to an attachment device located on the back of the boot. At least one lens group is moved in the direction of the optical axis thereof.