Types of RDPE feed

Time-based Events: Regular Classes and Sessions
These always have at least activity, location and startDate specified: so a Yoga class in Downtown Leisure Centre, at 7pm, on a Tuesday. See here for further clarification of the types available. 
The OpenActive Modelling Specification 2.0 represents regular events using a hierarchy of types: EventSeries, SessionSeries, and ScheduledSession, linked via the superEvent and subEvent properties. These are described by example in the diagram below:
Property inheritance
The ScheduledSession will inherit the properties of the SessionSeries, and the SessionSeries will inherit the properties of the EventSeries.
This means that if an EventSeries is not supplied, its details must be included on the SessionSeries.
Property inheritance overrides
The OpenActive Modelling Specification 2.0 represents regular events using a hierarchy of types: EventSeries, SessionSeries, and ScheduledSession. These are described by example in the diagram below:
Permissible configurations
A SessionSeries must always be supplied, including details that would otherwise be present in an EventSeries if no EventSeries is supplied.
In order for data to be bookable a ScheduledSession must be supplied, either embedded, within a separate feed, or generated through a Schedule.
For large providers with many events that are described identically but occur in the same location or in different locations, an EventSeries should be used to group these together. This avoids seemingly duplicate search results from a single provider. 
Exposing the model in feeds
For systems targeting small providers, the ScheduledSession may be embedded in the SessionSeries or visa versa.
For systems targeting large providers or small providers with high volumes of sessions, the ScheduledSession is highly recommended to be provided in a separate feed to the SessionSeries. This will reduce data transfer volumes significantly.
The EventSeries is unlikely to change frequently enough compared with the SessionSeries to warrant its own feed, and so can usually be embedded in the SessionSeries.
For bookable data, the possible feed combinations are described in the diagram below:
Please note that the first two "combined feed" options given above are no longer recommended for new OpenActive implementations. These options increase complexity for data users, and create unnecessary additional load on all systems.
Bookable data feed examples:
Small provider: SessionSeries with ScheduledSession​
Small provider (inverted): ScheduledSession with SessionSeries​
Small provider (high volume):
​SessionSeries and ScheduledSession (physical)
​SessionSeries and ScheduledSession (virtual)
Large provider: SessionSeries with EventSeries, and ScheduledSession​
Listings data feed examples:
Small provider: SessionSeries​
Large provider: SessionSeries with EventSeries​
Use of @id and superEvent for split feeds
When referencing data across feeds (such as between SessionSeries and ScheduledSession), the value of the @id must be used.
An @id is a globally unique identifier which must be in URL format for the purposes of namespacing. The @id does not need to resolve to a functional endpoint, but must use a domain name controlled by the organization or system publishing the data. See here for more information.
So for a minimal implementation simply invent a URL pattern that includes your domain for use as your @id, such as:
"https://id.ourparks.org.uk/api/session-series/1234"
For example within a SessionSeries feed, the SessionSeries @id is defined for each data item:
"data": {
  "@context": "https://openactive.io/",
  "@type": "SessionSeries",
  "@id": "https://id.ourparks.org.uk/api/session-series/1234",
  ...
}
And within a corresponding ScheduledSession feed, that SessionSeries @id is referenced by the superEvent property:
"data": {
  "@context": "https://openactive.io/",
  "@type": "ScheduledSession",
  "@id": "https://id.ourparks.org.uk/api/session-series/1234#/subEvent/C5EE1E55-2DE6-44F7-A865-42F268A82C63",
  "superEvent": "https://id.ourparks.org.uk/api/session-series/1234",
  ...
}
Time-based Events: Ad-hoc Events
The OpenActive model allows for ad-hoc events to be described using the pattern below. Ad-hoc events must only be used to describe truly ad-hoc events, and not to describe regular events such as those described in the previous section. See here for further clarification of the types available. 
Summary of ad-hoc event types
The OpenActive Modelling Specification 2.0 represents ad-hoc events using a hierarchy of types: EventSeries and Event, linked via the superEvent and subEvent properties. These are described by example in the diagram below:
Property inheritance
The Event will inherit the properties of the EventSeries.
This means that if an EventSeries is not supplied, its details must be included on the Event.
Permissible configurations
An Event must always be supplied, including details that would otherwise be present in an EventSeries if no EventSeries is supplied.
For large providers with many events that are described identically but occur in the same location or in different locations, an EventSeries should be used to group these together. This avoids seemingly duplicate search results from a single provider.
Exposing the model in feeds
Systems must include Events in stand-alone feeds separate from ScheduledSessions and  SessionSeries.
The EventSeries is unlikely to change frequently enough compared with the Event to warrant its own feed, and so can usually be embedded in the Event.
For bookable data, example feed combinations are described in the diagram below:
Bookable data feed examples:
Events only: Event​
Slot-based Events: FacilityUses
These always have at least activity andlocation specified, where the activity can be booked in slots: so a Tennis at Downtown Leisure Centre with slots available hourly from 8am until 8pm.
Two different levels of granularity are available: A FacilityUse represents "Badminton at Downtown Leisure Centre", where as IndividualFacilityUse is "Court 2 in Sports Hall 3 for Badminton at Towntown Leisure Centre".
The OpenActive Modelling Specification 2.0 represents slot-based events using a hierarchy of types: FacilityUse/IndividualFacilityUse and Slot, linked via the facilityUse and event properties.
For facilities a publisher must implement the following two independent feeds:
http://www.example.org/feeds/facility-uses 
​FacilityUse example (including IndividualFacilityUse)
http://www.example.org/feeds/individual-facility-use-slots
​Slot example​
Note that the above examples publish Slot availability at the IndividualFacilityUse level, which is now recommended for all new feeds.
Use of @id and facilityUse for split feeds
When referencing data across feeds (such as between FacilityUse and Slot), the value of the @id must be used.
An @id is a globally unique identifier which must be in URL format for the purposes of namespacing. The @id does not need to resolve to a functional endpoint, but must use a domain name controlled by the organization or system publishing the data. See here for more information.
So for a minimal implementation simply invent a URL pattern that includes your domain for use as your @id, such as:
"https://id.bookingsystem.com/api/facility-uses/1402CBP20150217/individual-facility-uses/1"
For example within a FacilityUse feed, the FacilityUse @id is defined for each data item, and IndividualFacilityUse @id  values are defined within these:
"data": {
  "@context": "https://openactive.io/",
  "@type": "FacilityUse",
  "@id": "https://id.bookingsystem.com/api/facility-uses/1402CBP20150217",
  "individualFacilityUse": [
    {
      "@type": "IndividualFacilityUse",
      "@id": "https://id.bookingsystem.com/api/facility-uses/1402CBP20150217/individual-facility-uses/1",
      "name": "Main Tennis Court 1"
    }
  ],
  ...
}
And within a corresponding Slot feed, that IndividualFacilityUse @id is referenced by the facilityUse property:
"data": {
  "@context": "https://openactive.io/",
  "@type": "Slot",
  "@id": "https://id.bookingsystem.com/api/facility-uses/1402CBP20150217/individual-facility-uses/1#/event/2018-03-01T10:00:00Z",
  "facilityUse": "https://id.bookingsystem.com/api/facility-uses/1402CBP20150217/individual-facility-uses/1",
  ...
}
Other types of Time-based Events: Headline Events and Courses
A feed of  HeadlineEvent can be used to represent whole day or multi-day events, such as mass participation events, family fun days, etc.
The OpenActive Modelling Specification 2.0 represents these events using a hierarchy of types: HeadlineEvent (for the overall event) and Event (for small events within the overall event) linked via the superEvent and subEvent properties.
See here for further clarification, and here for an example.
A feed of CourseInstance can be used to represent a fixed-length course.
The OpenActive Modelling Specification 2.0 represents these events using a hierarchy of types: CourseInstance (for the whole course) and Event (for the individual occurrences) linked via the superEvent and subEvent properties.
See here for further clarification, and here for an example.
Event relationship overview
The following diagram illustrates the relationships between the event types available within the OpenActive Modelling Specification 2.0:
Note the use of aliases (e.g. "IndividualFacilityUseSlot") which are useful when referring to a specific type that is being used in a particular context.
The relationship between all types is represented via the superEvent and subEvent properties, with the exception of:
FacilityUse/IndividualFacilityUse and Slot, which are linked via the facilityUse and event properties 
FacilityUse and IndividualFacilityUse, which are linked via the aggregateFacilityUse and individualFacilityUse properties.
Schema.org type inheritance overview
The model itself (the properties within the types) follows a different inheritance structure to the property inheritance structure described above.
EventSeries, SessionSeries, ScheduledSession, HeadlineEvent, CourseInstance, and Slot all sub-class Event.
This can be useful for modelling the entities within certain frameworks.