diff --git a/01.md b/01.md
index 5823119e..34027601 100644
--- a/01.md
+++ b/01.md
@@ -79,7 +79,7 @@ Specific ranges define storage behaviors:
 | Ephemeral     | `20000 <= kind < 30000`           | Nothing                                                |
 | Parameterized | `30000 <= kind < 40000`           | The newest event for each `pubkey`, `kind` and `d`-tag |
 
-Parameterized Replaceable events MUST include a `d`-tag with an identifier value to be used as a reference. Tag values that reference the newest replaceable MUST use this format: `<kind>:<32-byte lowercase hex of a pubkey>:<d-tag value>`.
+Parameterized Replaceable events MUST include a `d` tag with an unmodifiable identifier as value to be used as a reference. Tag values that reference the newest replaceable event MUST use this format: `<kind>:<32-byte lowercase hex of a pubkey>:<d-tag value>`. The `d` tag MUST be unique within the same kind and pubkey.
 
 In case of replaceable events with the same timestamp, the event with the lowest `.id` (first in lexical order) SHOULD be retained. Older versions MAY be kept but SHOULD not be returned on queries.