diff --git a/33.md b/33.md
index 4ebabc40..6b05bd06 100644
--- a/33.md
+++ b/33.md
@@ -10,6 +10,8 @@ This NIP adds a new event range that allows for replacement of events that have
 
 Implementation
 --------------
+The value of a tag is defined as the first parameter of a tag after the tag name.
+
 A *parameterized replaceable event* is defined as an event with a kind `30000 <= n < 40000`.  
 Upon a parameterized replaceable event with a newer timestamp than the currently known latest
 replaceable event with the same kind and first `d` tag value being received, the old event
@@ -26,6 +28,8 @@ replace each other:
 * `"tags":[["e"]]`: same as no tags
 * `"tags":[["d","test","1"]]`: only the value is considered (`test`)
 
+Clients SHOULD NOT use `d` tags with multiple values and SHOULD include the `d` tag even if it has no value to allow querying using the `#d` filter.
+
 Client Behavior
 ---------------