NIP-3166: Country code tag based on ISO-3166

3166.md

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+# Country Code NIP-3166
+
+`draft` `author:steliosrammos`
+
+This NIP defines a standard country code 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
+	]
+}
+```