In grassroots social governance, the "Four Actuals" typically includeactual population, actual houses, actual entities/units, and actual facilities(or similar local variants). "Actual amount of money" is financial data and not one of the core physical/subject entities required for refined social governance, so D is not included.

Municipal big-data centers own the cross-department data integration responsibility and operate the IOC as the city's digital nerve center.

BaaS (Blockchain-as-a-Service) is a platform service that provides blockchain capabilities for applications, thus classified as PaaS.

TheShanghai Three-Year Action Plan for Urban One-Network Managementdefines these four centers as the core structure: discovery (event identification), dispatch (coordination), handling (execution), and analysis (insight), forming a closed governance loop.

AI has undergone three major growth waves (1950-60s, 1980s, and 21st century deep learning) and two "AI winters" (1970s and late 1980s).