A method and apparatus are provided for detecting faults in a queue in a digital system. A second amplifying circuit in the amplifying stage may generate a second differential output signal that may be communicated to a second output of the amplifying stage. A cover for the zipper pull includes a housing having an aperture formed therein. The insulating member has a second aperture, an inside surface and an outside surface. Changes to the \u201c3D Model\u201d for appearance, geometric transformations, lighting, and additiondeletion of sub-objects are supported for collaborative usage. The lighter includes a fuel tank which can be either fixed or removable as for instance fuel gas cartridges.