ChronoMark VR-3 is a covert isotopic tagging system administered through Tessera Corponation's mandatory annual biometric registration events, colloquially called 'Census Days.' During the registration process, subjects receive a subcutaneous injection ostensibly containing a standard immunological registry marker. In practice, the injection also delivers a proprietary isotopic tracer compound — a stable, non-radioactive rare-earth chelate — that binds to keratinocytes and persists in shed skin cells, hair follicles, and exhaled particulate for 14 to 18 months. Tessera's licensed scanner infrastructure, embedded in door frames, HVAC intake grilles, and transit turnstiles, can detect the unique isotopic ratio of an individual's tag from ambient environmental samples without any direct contact or subject awareness.