Source: Schema.org v30.1 vocabulary. Official byDay property definition.
What does byDay mean?
Defines the day(s) of the week on which a recurring [[Event]] takes place. May be specified using either [[DayOfWeek]], or alternatively [[Text]] conforming to iCal's syntax for byDay recurrence rules.
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