A light-shielding packaging for a roll of continuous photosensitive web wound on a core having on its each end a light-shielding flange disc has at its leading end a light-shielding leader sheet. In the electrode, a light emitting aperture is formed. A counter portion is formed near a groove bottom of the inner raceway surface. The second plate has a first arm that extends across the throat to secure the generally vertical member within, and a second arm that moves into alignment with the notch, concurrent with movement of the second plate. This can include discovery of other related services and employment of common web protocols to communicate between the services.