diff --git a/73.md b/73.md
index 7fb9a3c3c5..80cbe9ea0f 100644
--- a/73.md
+++ b/73.md
@@ -16,6 +16,7 @@ There are certain established global content identifiers such as [Book ISBNs](ht
 | Type                   | `i` tag                                                    | `k` tag                  |
 | ---                    | ---                                                        | ---                      |
 | URLs                   | "`<URL, normalized, no fragment>`"                         | "web"                    |
+| Relay                  | "`<WebSocket URL, normalized>`"                            | "relay"                  |
 | Books                  | "isbn:`<id, without hyphens>`"                             | "isbn"                   |
 | Geohashes              | "geo:`<geohash, lowercase>`"                               | "geo"                    |
 | Movies                 | "isan:`<id, without version part>`"                        | "isan"                   |