https://www.w3.org/TR/activitystreams-vocabulary/#extendedtypes https://www.w3.org/TR/activitystreams-vocabulary/#extendedty... > Support for specific extended

https://www.w3.org/TR/activitystreams-vocabulary/#extendedtypes https://www.w3.org/TR/activitystreams-vocabulary/#extendedty... > Support for specific extended vocabulary types is expected to vary, with implementations only selecting the extended types and properties that make sense within the specific context and requirements of those applications. However, to avoid possible interoperability issues, implementations must avoid using extension types or properties that unduly overlap with or duplicate the extended vocabulary defined here.