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.

BG004.11

Country / Post Bulgaria
Date of Issue 1 April 2011
Primary theme Astronomy & Space (Astronomy)
Subject The Day of Humour and Joke - 35 Years since the Discovery of the Tiny Planet of Gabrovo
Width 53.5 mm
Height 28.5 mm
Denomination 0.65 BGL
Number in set 1
Layout/Format sheet of 4
Perforations 12.5 by 12.5
Stamp issuing authority Bulgaria Posts PLC
Printer Bulgarian Philately and Numismatics