diff --git a/spec/light-client/supervisor/supervisor_001_draft.md b/spec/light-client/supervisor/supervisor_001_draft.md
index 8a3ab28d2..529bd72f3 100644
--- a/spec/light-client/supervisor/supervisor_001_draft.md
+++ b/spec/light-client/supervisor/supervisor_001_draft.md
@@ -208,7 +208,7 @@ initialization. Initially this set is partitioned into
 
 - one full node that is the *primary* (singleton set),
 - a set *Secondaries* (of fixed size, e.g., 3),
-- a set *FullNodes*.
+- a set *FullNodes*; it excludes *primary* and *Secondaries* nodes.
 - A set *FaultyNodes* of nodes that the light client suspects of
     being faulty; it is initially empty