nips/3166.md

# Country Code NIP-3166

`draft` `author:steliosrammos`

This NIP defines a standard geo-location tag for events.

## `c tag`

The [ISO3166-1 Alpha-2](https://en.wikipedia.org/wiki/ISO_3166-2) standard can be used for a universally recognised country codes.

`[“c”, “<ISO3166 alpha-2  country code>”]`

The tag can be added on any event, and the meaning may vary (see [Examples](#examples) below). The advantage of having a tag specifically for location is to allow Nostr clients to easily query/filter content by location, and for Relays to index events by that tag.

## Examples

### On `kind:0`

The `c` tag can be added to profiles through the `kind:0` event. Nostr clients can display the location on the profile page of the user (similar to Twitter/X profiles).

```json
{
	"kind":  0,
	"tags": [
		[“c”, “GR”]  # Greece Country Code
	]
}
```

### On `kind:1`

On `kind:1` events the `c` tag can be used as a status for the post (similar to Instagram posts with a location).

```json
{
	"kind":  1,
	"content": "Enjoying a beer paid in Bitcoin at Bitcoin Beach."
	"tags": [
		[“c”, “ES”]  # El Salvador Country Code
	]
}
```