A feature named \u201catrial tracking recovery\u201d provides for restoring delivery of cardiac pacing therapy upon identification of an atrial refractory sense-ventricular sense pattern of cardiac activity. Additional rectification circuits and LED series sets can be added in parallel to the first in \u201cstacked mode\u201d, with each rectification circuit and LED series set electrically independent of prior and subsequent circuits. Since leaking out to an aperture formed on an outer surface of the light-condensed surface of this light spot, near field light is scattered by a micro metal member. The certificate list includes individual and group certificates, and the certificate includes specifying information on a certification target, a public key and signature by an responsible person of a group, to which the certification target belongs.