Construction
Individual stamps are separated manually rather than torn along punched holes.
Type study · separation
Imperforate stamp
A stamp form issued without perforations, making the cut margin part of both handling and later inspection.
What survives
Margins can retain clues about spacing and how closely the item was cut. A detached stamp no longer preserves its exact original sheet position unless other evidence supports it.
Documented anchor
The 1840 Penny Black was printed in sheets and cut apart. It offers a clear early example without implying that every imperforate stamp shares its design or production details.
Evidence: npm-world-first