A portable, manually operable, trigger-activated pump spray applicator can be used to apply paints and coating fluids in commercial and military end use applications, especially chemical agent resistant coating fluids. In response to the reception of the stop instruction, the second thread terminates execution of a first method in execution and initiates execution of the second method which should be executed subsequent to the first method. Therefore, the gateway apparatus having an advanced versatility can be provided. The elongated slat may also be shorter than the channel portions of the side rail to permit the slat to slide within the channel during operation of the cover system.