diff --git a/rpc/gnmi/gnmi-specification.md b/rpc/gnmi/gnmi-specification.md
index d164ca9..1e9d894 100644
--- a/rpc/gnmi/gnmi-specification.md
+++ b/rpc/gnmi/gnmi-specification.md
@@ -1638,6 +1638,10 @@ with one of the following `modes`:
     driven (e.g., the changing of state of an entity based on an external
     trigger) then an `ON_CHANGE` subscription may be created, whereas if other
     data represents counter values, a `SAMPLE` subscription may be created.
+    The target is expected to choose and change a `sample_interval` dynamically.
+    If `sample_interval` is specified in the subscribe request, the target
+    `SHOULD` reject the subscription by closing the Subscribe RPC specifying an
+    `InvalidArgument (3)` error code.
 
 ##### 3.5.1.5.3 POLL Subscriptions