diff --git a/readme.md b/readme.md
index 3d4b761..132bd04 100644
--- a/readme.md
+++ b/readme.md
@@ -131,10 +131,10 @@ When `sig` is null (typically for archived MST sub-trees), this STAR cannot be c
     - `v` (hash link, **nullable**): reference to the record data for this key.
       - when **null**: the record is included in the archive and will follow (implicit CID)
       - when **non-null**: the record exists but is not included in the archive
-    - `t` (hash link, nullable): link to a subtree that sorts to the right of this entry's key and to the left of the next entry's key. same rules as `l`:
-      - when **absent**: there is no left subtree
-      - when **null**: the left subtree is present and will follow in the archive (implicit CID)
-      - when **non-null**: the left subtree exists but is abset from the archive
+    - `t` (hash link, **optional and nullable**): link to a subtree that sorts to the right of this entry's key and to the left of the next entry's key. same rules as `l`:
+      - when **absent**: there is no subtree here subtree
+      - when **null**: the subtree is present and will follow in the archive (implicit CID)
+      - when **non-null**: the subtree exists but is abset from the archive
 
 
 ### record