I run a convention's website

Your convention has dates, a venue, a schedule and a ticket link. You want all of that in people's calendars and on every listing site, and you want it to stay right when something changes.

What you're dealing with now

• Everyone copies you by hand. Listing sites, local calendars and fan wikis type your dates in themselves. Some get the timezone wrong, and some never notice when you move a day.
• "Add to calendar" is a snapshot. Attendees who pressed it have the dates from the day they pressed it.
• Every listing site has its own form, and you fill in all of them, again for every change.
• No dates yet means no listing. Most forms want a day, so until you have one, the convention can't be listed at all.

Publish once, show up everywhere

You publish one document on your own website. Everything that reads Open Evnt picks it up from there:

• Calendar apps (I'm building a calendar app): an attendee pastes your page's link and has the convention. The app can fetch it again later, so a moved day reaches their calendar.
• Event directories (I run an event directory) that follow your site list the convention with your dates, as you wrote them.
• Ticketing sites (I build a ticketing site) that sell your tickets can point their listing at yours with an alternate relation, so apps know it's the same convention.

You stay the source. Change the document, and everyone reading it gets the change.

What you can say

• Dates as precise as you know them. The year, then the month, then the days and times.
• The name in every language your attendees speak.
• The schedule, with each panel or show as an activity.
• What fell through. A cancelled panel, a cancelled day, or the whole convention postponed, without deleting anything.
• The convention across the years. Each edition points at a document for the whole series.
• Anything else, as a component of your own.

What it costs you

One JSON file on your web server and one line in your page's <head>. No account, no platform to sign up for. Check the file in the Playground before you publish.

How

{
	"v": "0.2",
	"id": "https://harbourcon.example/2027/event.evnt.json",
	"name": { "en": "Harbour Comic Con 2027", "fr": "Harbour Comic Con 2027" },
	"venue": {
		"name": { "en": "Halifax Convention Centre" },
		"address": "1650 Argyle Street, Halifax, NS",
		"countryCode": "CA"
	},
	"occurrences": [
		{
			"start": "2027-08-13T10:00[America/Halifax]",
			"end": "2027-08-15T18:00[America/Halifax]",
			"activities": [
				{ "name": { "en": "Opening ceremony" } },
				{ "name": { "en": "Cosplay contest" } }
			]
		}
	],
	"components": [
		{
			"$type": "directory.evnt.component.link#0",
			"url": "https://harbourcon.example/tickets",
			"name": { "en": "Tickets", "fr": "Billets" }
		},
		{
			"$type": "directory.evnt.component.relation#0",
			"type": "parent",
			"target": "https://harbourcon.example/series.evnt.json"
		}
	]
}

id

Use the https URL the document is served from (§2.2). Never change it, even if you move the file. Redirect the old URL instead.

Next year's convention is a new event. Copy this year's document if you like, but give the copy a new id.

name and the series

Put the year or edition in the name, as you'd write it on a poster. The convention as a whole, across all years, can have its own document, like series.evnt.json with just a name. Each year points at it with a parent relation.

venue

An event has one venue. If day one is in the convention centre and day two is in a park across town, that's two events (§4). Point both at the same parent.

dates

If you only know the month so far, write 2027-08[America/Halifax] and make it more precise later. Use the venue's timezone at every precision.

If doors open at different times for different tickets, start and end cover the widest window: the earliest anyone gets in, the latest anyone may stay (§5).

schedule

Panels and shows go in activities. A panel that's called off gets "status": "cancelled", and the rest of the convention goes on.

description and poster

Add a Markdown component for the description and a splash media component with "roles": ["poster"] and alt text.

cancelled or postponed

Set status and keep the document where it is, with its last dates (§2.1). Don't delete it, since apps that already have it need to see the change. When a postponed convention gets new dates, update occurrences and remove status.

events inside the convention

A meetup or an after-party at the convention can be its own event with a parent relation to the convention. The convention can list them with child relations.

publishing

• Serve the file as .evnt.json with Content-Type: application/vnd.evnt+json and Access-Control-Allow-Origin: *. See HTTP.
• On the convention's web page, add <link rel="alternate" type="application/vnd.evnt+json" href="/2027/event.evnt.json"> to the <head>, so apps find the document from the page URL (Link Discovery).
• If a listing site has its own document about your convention, either side can add an alternate relation to the other.