CH 2001 Stamp Day Basel BS, cover cancelled 7.-9.12.2001 4000 Basel - with signature

Switzerland 2001 Stamp Day Basel BS,
official cover "Moderne Architektur in Basel - Tag der Briefmarke - Journée du Timbre - Giornata del Francobollo - Di dalla Marca Postala- BASILEA 2001 - Offizielle Ausgabe VSPhV / FSPS / FSFS", 
with Stamp Day stamp, without address, cancelled "7.-9.12.2001 4000 Basel - Tag der Briefmarke - Basilea 2001", with the signature of the stamp designer Beat Kehrli, luxury conservation.