Glossary
Quarantine attribute (com.apple.quarantine)
The com.apple.quarantine extended attribute on downloaded files: flags, hex time, agent name and a UUID that joins to the database.
com.apple.quarantine is an extended attribute stored on the downloaded file itself. Its value has four semicolon-separated fields, flags;time;agent;uuid, for example 0083;66f7c2a1;Safari;6E4C2B1A-.... The flags are a hexadecimal bit field, the time is hexadecimal Unix seconds (UTC), the agent is the application name, and the UUID, which may be empty, matches LSQuarantineEventIdentifier in QuarantineEventsV2.
Archive Utility copies the archive's value, UUID included, to the files it extracts, so one event can cover several files. Copies within APFS or HFS+ keep the attribute. xattr -d com.apple.quarantine or xattr -c remove it without touching the database. For exact bytes, collect it with xattr -r -l -x. See com.apple.quarantine flags explained.