diff --git a/specification/common/common.md b/specification/common/common.md
index 7cedad5f3f5..d011bbba231 100644
--- a/specification/common/common.md
+++ b/specification/common/common.md
@@ -90,6 +90,13 @@ Names SHOULD follow these rules:
 - When a new namespace is necessary consider whether it should be a top-level
   namespace (e.g. `service`) or a nested namespace (e.g. `service.instance`).
 
+- Semantic conventions exist for 4 areas: for Resource, Span and Log attribute
+  and for Metric label keys. Identical namespaces or names in these areas MUST
+  have identical meanings. For example the `http.method` span attribute name
+  denotes exactly the same concept as the `http.method` metric label, has the
+  same data type and the same set of possible values (in both cases it records
+  the value of the HTTP protocol's request method as a string).
+
 - Semantic conventions MUST limit names to printable Basic Latin characters
   (more precisely to
   [U+0021 .. U+007E](https://en.wikipedia.org/wiki/Basic_Latin_(Unicode_block)#Table_of_characters)