Source: Schema.org v30.1 vocabulary. Official dateRead property definition.
What does dateRead mean?
The date/time at which the message has been read by the recipient if a single recipient exists.
Used on types (domainIncludes)
Expected value types (rangeIncludes)
Schema.org domainIncludes and rangeIncludes are descriptive guidance, not strict validation prohibitions. Check the official reference for updates.
Related reference
Browse all Schema.org types and properties · Google feature support status