The World Association for the Development of Philately (WADP) and the Universal Postal Union (UPU) jointly conceived and developed the WADP Numbering System - WNS, which was launched on 1 January 2002.

PT109.17

Country / Post Portugal
Date of Issue 20 September 2017
Primary theme Architecture (Modern)
Subject Our Cities II - Porto - Casa da Música
Width 40.0 mm
Height 30.6 mm
Denomination 0.50 €
Number in set 4 (show set)
Layout/Format sheet of 50
Perforations 13 by 13
Stamp issuing authority CTT Correios de Portugal SA
Printer Cartor Security Printing
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