The Sixth Definitive Issue, at present current, was put on sale on 3rd September 1979 with the release of a 30p stamp. Issued singly or in lots, the sixteen denominations released so far portray the theme 'Agriculture and Rural Development'.
Layout : The stamps of this series were printed in three sizes:
a. Small size: 15p,20p,30p, (Gandhi), 30p (Nehru), 35p (Gandhi), 35p (Nehru)and 35p (Family Planning) in vertical format in overall size of 2.03x2.28 cms and printing size of 1.72x1.98 cms and 2p, 5p,10p,25p,30p (Harvesting) and 50p in horizontal format in same size. All values were issued in sheet of 100 (10x10). The printers sheet consisted of 400 stamps arranged in 4 panes of 100 stamps each.
b. Medium size: 1Re and 2Rs were in overall size of 2.05x3.1 cms and printing size of 1.65x2.75 cms in vertical format in sheets of 70 (10x7). The printers sheet consisted of 280 stamps arranged in 4 panes of 70 stamps each.
c. Large size: Rs 2.25, Rs2.80 and 5 Rs values were printed in overall size of 2.3x4.05 cms and printing size of 1.9x3.7 cms in vertical format and issued in sheets of 50(10x5). The printers sheet consisted of 200 stamps arranged in 4 panes of 50 stamps each.
Printing: All denominations were printed in photogravure and 2p was also printed by offset-litho. All Paise denominations, 1Re and 2Rs value were printed in single colour and Rs 2.25, Rs 2.80 and 5Rs values were printed in two colours.
Paper and watermark: All values of this series except 2p, 5p and 15p were on 'Multiple Asokan Capital' watermarked paper. 2p, 5p and 15p were printed on modified 'Large star & India Govt.'(W4) watermarked paper , but W3 watermarked paper was also used haphazardly in printings. When printings of a denominaion occur on paper with different watermarks, these are listed as varieties. When printings from same cylinder occur on paper with different watermarks, these are also listed as varieties.
Indigenous 'Multiple Asokan Capital' watermarked paper was to print all remaining values and 2p, 5p and 15p values were also issued on this paper from25th March 1981. Paise vaues in small vertical design were printed with watermark in upright position and small horizontal designs and rupee values were printed with watermark in sideways position - the Capital pointing to right when seen from front of the stamp. In case of 5Rs denomination both positions of the Capital - upright and sideways are appearing in large quantities (see varieties 670b 670c).
Imprint and Cylinder Numbers: Sheets of all values printed in photogravure bear printers imprints and cycinder numbers. Sheets of 2p value printed by offset-litho donot have any marginal inscriptions.
Perforation: All values are comb perforated small vertical designs and rupee values are perforated 141/2x14 and small horizontal designs 14x141/2.
Shades: Only those shades have been listed which are easily distiguishable.
Varieties: All prominent verieties listed and illustrated are those which we have actually seen. Their position in the sheet has been indicated followed by cylinder numbers and pane identification wherever possible.