1 Shi Jin - Flour Stamp Chengdu City, Sichuan

Chinese grain ration coupons (liangpiao) and commodity stamps of this type were administrative instruments of the planned economy, not currency — they entitled the bearer to purchase a fixed quantity of a staple commodity at a state-controlled price, and were non-transferable in theory if rarely in practice. By 1979, these coupons had been in continuous use since the 1950s rationing system established under the First Five-Year Plan, and local-issue stamps from city-level grain bureaus like this one were valid only within their administrative district, unlike the national-issue liangpiao that permitted inter-provincial travel purchases.

The Chengdu municipal series from this period was produced locally rather than through a centralized security printer, which accounts for the relatively simple authentication — an embossed or inked official seal rather than intaglio printing or watermarked paper. Sichuan provincial and Chengdu city-level stamps are among the more systematically collected of the regional issues, owing to the province's large population and the resulting volume and variety of denominations printed.