The 1997-SG, Part 18, lists and assigns stamp numbers in chronological order for commemorative stamps; however, it periodically lists "definitive stamps" and any respective "Coil stamps", by a group of stamp numbers, inserted about every five-years of issue.

Souviner Sheets, which Stanely Gibbons calls "Miniature Sheets" are assigned an "MS----" number, using the next sequential number available.