CH 1979 Stamp Day Rorschach SG, cover cancelled 10.12.79 1211 Geneve Nations Unies (UNO Geneva CH)

Switzerland 1979 Stamp Day Rorschach SG,
official cover "Tag der Briefmarke - Di dalla Marca postala - Journée du Timbre - Giornata del Francobollo - Rorschach 1979 -
illustration Kloster Mariaberg - Refectorium, Offizielle Ausgabe VSPhV / USFS / USPhS",
with UNO-Genva Cachet-cancellation "Postverwaltung der Vereinten Nationen Rorschach 1.12.1979",
registered mail cancelled "10.12.79 1211 Geneve Nations Unies" (UNO Genf CH),
backside arrival cancellation "11.12.79 6052 Hergiswil", luxury conservation.