diff --git a/24.md b/24.md
index 8710af69..ef4196bd 100644
--- a/24.md
+++ b/24.md
@@ -40,5 +40,5 @@ tags
 These tags may be present in multiple event kinds. Whenever a different meaning is not specified by some more specific NIP, they have the following meanings:
 
   - `r`: a web URL the event is referring to in some way
-  - `i`: an external id the event is referring to in some way - see [NIP-XX](XX.md)
+  - `i`: an external id the event is referring to in some way - see [NIP-73](73.md)
   - `title`: name of [NIP-51](51.md) sets, [NIP-52](52.md) calendar event, [NIP-53](53.md) live event or [NIP-99](99.md) listing
diff --git a/XX.md b/73.md
similarity index 99%
rename from XX.md
rename to 73.md
index e7ee5f57..12228d36 100644
--- a/XX.md
+++ b/73.md
@@ -1,4 +1,4 @@
-NIP-XX
+NIP-73
 ======
 
 External Content IDs
diff --git a/README.md b/README.md
index 550888a8..6c83ba88 100644
--- a/README.md
+++ b/README.md
@@ -77,6 +77,7 @@ They exist to document what may be implemented by [Nostr](https://github.com/nos
 - [NIP-70: Protected Events](70.md)
 - [NIP-71: Video Events](71.md)
 - [NIP-72: Moderated Communities](72.md)
+- [NIP-73: External Content IDs](73.md)
 - [NIP-75: Zap Goals](75.md)
 - [NIP-78: Application-specific data](78.md)
 - [NIP-84: Highlights](84.md)
@@ -238,7 +239,7 @@ They exist to document what may be implemented by [Nostr](https://github.com/nos
 | `-`               | --                                   | --                              | [70](70.md)                           |
 | `g`               | geohash                              | --                              | [52](52.md)                           |
 | `h`               | group id                             | --                              | [29](29.md)                           |
-| `i`               | identity                             | proof                           | [39](39.md)                           |
+| `i`               | external identity                    | proof, url hint                 | [39](39.md), [73](73.md)              |
 | `k`               | kind number (string)                 | --                              | [18](18.md), [25](25.md), [72](72.md) |
 | `l`               | label, label namespace               | --                              | [32](32.md)                           |
 | `L`               | label namespace                      | --                              | [32](32.md)                           |