Educational Calendar Events — integration guide

Status: DRAFT. This guide specifies the Edufeed extension of NIP-52 ("NIP-52-Edufeed") based on the agreements in edufeed-app issue #13. Attribute semantics follow the issue agreements; the tag names (registrationRequired, price, eventAttendanceMode, educationalLevel:*) are fixed. Nothing here is implemented on the relays yet — see Status.

This guide covers the write side of educational calendar events: how to publish NIP-52 calendar events enriched with educational metadata into the Edufeed data pool. The read side — fetching and rendering — is shown in the Educational Calendar Events live demo. Both describe the same events (the demo reads the plain NIP-52 events published today; the extension attributes below are a draft).

It is the calendar counterpart of the Educational Data Pool integration guide, which covers AMB resources (kind 30142 / NIP-AMB). Calendar events use the standard Nostr calendar kinds and stay fully readable for any NIP-52 client; the educational attributes are additive.

1. Base format: NIP-52

Educational events are ordinary NIP-52 events. Two kinds carry the events themselves (both are addressable, identified by kind:pubkey:d-tag, and updated by re-publishing the full event — same mechanics as described in Section 4 of the data-pool guide):

Kind	Meaning	`start` / `end` format
`31922`	date-based (full-day / multi-day)	`YYYY-MM-DD` (`end` exclusive)
`31923`	time-based	unix timestamp seconds, plus optional `start_tzid` / `end_tzid`

Standard NIP-52 tags used on Edufeed events today (as found live on the relay):

["d", "<stable event id, often the source URL>"]
["title", "<event title>"]
["start", "..."] ["end", "..."] ["start_tzid", "Europe/Berlin"]
["summary", "<short description>"]          // long form goes into content
["location", "<place or meeting URL>"]
["image", "<preview image URL>"]
["r", "<link to the event page>"]           // repeated
["t", "<hashtag>"]                          // repeated

Everything in the next section comes on top of this.

2. The Edufeed extension ("NIP-52-Edufeed")

NIP-52 itself has no fields for registration, cost, attendance mode, or educational classification. The Edufeed working group agreed on the following attributes (issue #13, calls of 2025-03-25 and 2025-05-22). Two tag styles are used, on purpose:

Plain event attributes (registration, price, mode) are flat tags with schema.org-aligned camelCase names where a schema.org counterpart exists (eventAttendanceMode, registrationRequired); price follows the NIP-15 / NIP-99 shape.
Vocabulary attributes (educational level, later: Bildungsbereiche, Zielgruppen) reuse the NIP-AMB flattening convention (<property>:id / <property>:prefLabel:<lang> / <property>:type concept triples), so the same tooling that reads kind 30142 resources — including amb-nostr-converter — can read them off calendar events. Their value lists are SKOS vocabularies published on nocabs.edufeed.org, Edufeed's Nostr vocabulary hosting — the same place the EKW vocabularies live (see ekw-metadata.md).

2.1 Registration (Anmeldung) — agreed: yes/no only

Whether attending requires signing up beforehand. Registration details (how, where, deadlines) belong in the description text and/or an r-tag linking to the event page — there is deliberately no structured registration-link field.

["registrationRequired", "true"]     // or "false"

Tag absent → no statement.

2.2 Cost (Kosten) — agreed: price + currency

Modelled on the price / currency fields of NIP-15, encoded as one tag (shape follows NIP-99's price tag):

["price", "<amount>", "<ISO-4217 currency>"]      // e.g. ["price", "0", "EUR"]

Agreed semantics:

`price` value	Meaning
tag absent / empty amount	keine Angabe (no statement)
`0`	kostenlos (free)
`> 0`	kostenpflichtig (paid)

There is no separate "Kostenbeschreibung" field and no isAccessibleForFree flag — anything beyond the number (reduced rates, member prices, "teilweise kostenpflichtig") goes into the description text. For events with differentiated pricing where no single number is honest, publish the tag without an amount statement (or the base price) and explain in the description. A structured per-audience price list (Personenkreis / Kosten / Währung) was discussed and deferred — see open questions.

2.3 Attendance mode (Modus) — agreed: online / offline / mix

Tag name and values are taken exactly from schema.org eventAttendanceMode:

["eventAttendanceMode", "https://schema.org/OnlineEventAttendanceMode"]

Issue-#13 term	Tag value
online	`https://schema.org/OnlineEventAttendanceMode`
offline	`https://schema.org/OfflineEventAttendanceMode`
mix	`https://schema.org/MixedEventAttendanceMode`

mix covers what other systems call blended or hybrid; details are expected on the organizer's event page.

2.4 Participants and roles — agreed: organizer / attendee

NIP-52 already defines participant p-tags with a role field. Edufeed supports (at least) these two roles:

["p", "<32-byte hex pubkey>", "<optional relay hint>", "organizer"]
["p", "<32-byte hex pubkey>", "<optional relay hint>", "attendee"]

Note: an attendee p-tag is set by the event author and is independent of NIP-52 RSVP events (kind 31925), which attendees publish themselves.

2.5 Educational level (Bildungsstufe) — vocabulary attribute

The stage of the education system the event addresses. Uses the AMB property name educationalLevel with the Bildungsstufe vocabulary on nocabs — a SKOS concept scheme that keeps the canonical KIM concept URIs (https://w3id.org/kim/educationalLevel/), so the :id values below are the same whether you resolve them via nocabs or via w3id.org. Flattened exactly as on kind 30142 resources (see Section 5 of the data-pool guide) — a concept triple per value, multi-valued by repeating the triple:

["educationalLevel:id", "https://w3id.org/kim/educationalLevel/level_C"]
["educationalLevel:prefLabel:de", "Fortbildung"]
["educationalLevel:type", "Concept"]

The vocabulary as served by nocabs (ISCED-2011-aligned where applicable):

Concept URI (`…/educationalLevel/`)	prefLabel de	prefLabel en
`level_0`	Elementarbereich	Early childhood education
`level_1`	Primarbereich	Primary education
`level_2`	Sekundarbereich I	Lower secondary education
`level_3`	Sekundarbereich II	Upper secondary education
`level_4`	Postsekundarer nicht-tertiärer Bereich	Post-secondary non-tertiary education
`level_5`	Kurzes tertiäres Bildungsprogramm	Short-cycle tertiary education
`level_A`	Hochschule	University
`level_6`	— Bachelor oder äquivalent (narrower of `level_A`)	Bachelor or equivalent
`level_7`	— Master oder äquivalent (narrower of `level_A`)	Master or equivalent
`level_8`	— Promotion oder äquivalent (narrower of `level_A`)	Doctoral or equivalent
`level_B`	Vorbereitungsdienst	Preparatory service
`level_C`	Fortbildung	Advanced training

As everywhere in the data pool: the :id URI is authoritative, :prefLabel:de is a denormalised display copy, :type is the literal Concept.

3. Worked example

A time-based (kind 31923) online training, free of charge, registration required, aimed at teacher training (Fortbildung) and preparatory service:

{
  "kind": 31923,
  "tags": [
    ["d", "https://relilab.org/relilab-werkstatt-2026-09/"],
    ["title", "reli.werkstatt – Du bist kostbar!"],
    ["start", "1789651800"],
    ["start_tzid", "Europe/Berlin"],
    ["end", "1789655400"],
    ["end_tzid", "Europe/Berlin"],
    ["summary", "Kurze thematische Inputs mit Austausch und Praxis. Anmeldung über relilab.org; Zugangslink nach Anmeldung."],
    ["location", "Zoom: https://relilab.org/live"],
    ["image", "https://relilab.org/wp-content/uploads/werkstatt.jpg"],
    ["r", "https://relilab.org/relilab-werkstatt-2026-09/"],
    ["t", "relilab"],

    ["registrationRequired", "true"],
    ["price", "0", "EUR"],
    ["eventAttendanceMode", "https://schema.org/OnlineEventAttendanceMode"],

    ["p", "<organizer pubkey hex>", "wss://relay.edufeed.org", "organizer"],

    ["educationalLevel:id", "https://w3id.org/kim/educationalLevel/level_C"],
    ["educationalLevel:prefLabel:de", "Fortbildung"],
    ["educationalLevel:type", "Concept"],
    ["educationalLevel:id", "https://w3id.org/kim/educationalLevel/level_B"],
    ["educationalLevel:prefLabel:de", "Vorbereitungsdienst"],
    ["educationalLevel:type", "Concept"]
  ],
  "content": "Die reli.werkstatt bietet kurze thematische Inputs und die Möglichkeit zu Austausch und Praxis.\n\nAnmeldung erforderlich (kostenlos): https://relilab.org/relilab-werkstatt-2026-09/"
}

A NIP-52 client that knows nothing about the extension renders this as a normal calendar event; an education-aware client can additionally filter and display registration, cost, mode, and Bildungsstufe.

A second, complete example built from a real relilab event lives in examples/relilab-impuls-kirchengeschichte-suedwesten-1.json.

4. Publishing

As with AMB resources, any client that can sign for the author can publish — directly with the private key, via NIP-07 (browser extension), or via NIP-46 (remote signer). End-to-end from the command line with nak:

nak event -k 31923 \
  -d "https://example.org/events/my-training" \
  -t "title=Einführung in OER" \
  -t "start=1789651800" \
  -t "start_tzid=Europe/Berlin" \
  -t "registrationRequired=true" \
  -t "eventAttendanceMode=https://schema.org/OnlineEventAttendanceMode" \
  -t "price=0;EUR" \
  -t "educationalLevel:id=https://w3id.org/kim/educationalLevel/level_C" \
  -t "educationalLevel:prefLabel:de=Fortbildung" \
  -t "educationalLevel:type=Concept" \
  -c "Eine offene Fortbildung zu Open Educational Resources. Anmeldung: siehe Veranstaltungsseite." \
  --sec nsec1... \
  wss://dev.amb-relay.edufeed.org

(Multi-element tags like price use ; as separator in nak -t: -t "price=0;EUR" produces ["price", "0", "EUR"]. Alternatively, pipe a partial event JSON into nak event on stdin, or use one of the client libraries.)

The command above targets the development relay wss://dev.amb-relay.edufeed.org — use it while testing; real events go to the production relay wss://relay.edufeed.org.

Updates re-publish the full event under the same d-tag; deletion is NIP-09 (kind 5 with an a-tag 31923:<pubkey>:<d>), identical to the data-pool guide, Section 4.

5. Querying

Fetch by kind (a standard NIP-01 filter) and match the extension tags client-side:

// All calendar events (bounded; close the subscription on EOSE)
{"kinds": [31922, 31923], "limit": 500}

// Client-side: keep only events for a given educational level
const wanted = "https://w3id.org/kim/educationalLevel/level_C";
const hits = events.filter(ev =>
  ev.tags.some(t => t[0] === "educationalLevel:id" && t[1] === wanted));

Once the calendar relay indexes the new tag keys — part of the planned relay adaptation (issue #13: "Kalender-Relay anpassen") — the same selection works relay-side. Note that multi-character tag filters like the following go beyond plain NIP-01 (which only defines single-letter #x filters); they are an Edufeed relay extension, the same one the AMB relay already answers for keys like #about:id:

// Future, once the relay indexes the key — not implemented yet
{"kinds": [31922, 31923], "#educationalLevel:id": ["https://w3id.org/kim/educationalLevel/level_C"], "limit": 500}

Notes:

"Upcoming" cannot be filtered relay-side: since/until match created_at, not the start tag. Fetch and filter client-side (this is what the live demo does).

6. Status and open questions

Agreed in issue #13 (semantics): registration yes/no with details in the description; price + currency with the empty/0/>0 semantics; attendance mode online/offline/mix; p-tag roles organizer/attendee; educationalLevel as an additional vocabulary attribute.

Fixed tag names (decided 2026-07-06): registrationRequired (true/false), price (NIP-15 semantics, NIP-99 shape), eventAttendanceMode (name and values exactly as schema.org), educationalLevel:* (NIP-AMB concept triples).

Open / follow-ups:

Adapt the calendar relay (tag indexing for the new keys).
Structured per-audience pricing (Personenkreis/Kosten/Währung list) — could become repeated price tags with a label element; deferred, description text is the interim answer.
Further vocabulary attributes: Bildungsbereiche, Zielgruppen (audience) — like educationalLevel, each to be published as a SKOS vocabulary on nocabs.edufeed.org and flattened as NIP-AMB concept triples.
Import relilab dates into edufeed.

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calendar-integration.md

Educational Calendar Events — integration guide

1. Base format: NIP-52

2. The Edufeed extension ("NIP-52-Edufeed")

2.1 Registration (Anmeldung) — agreed: yes/no only

2.2 Cost (Kosten) — agreed: price + currency

2.3 Attendance mode (Modus) — agreed: online / offline / mix

2.4 Participants and roles — agreed: organizer / attendee

2.5 Educational level (Bildungsstufe) — vocabulary attribute

3. Worked example

4. Publishing

5. Querying

6. Status and open questions

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Educational Calendar Events — integration guide

1. Base format: NIP-52

2. The Edufeed extension ("NIP-52-Edufeed")

2.1 Registration (Anmeldung) — agreed: yes/no only

2.2 Cost (Kosten) — agreed: price + currency

2.3 Attendance mode (Modus) — agreed: online / offline / mix

2.4 Participants and roles — agreed: organizer / attendee

2.5 Educational level (Bildungsstufe) — vocabulary attribute

3. Worked example

4. Publishing

5. Querying

6. Status and open questions