diff --git a/doc/source/cloner.rst b/doc/source/cloner.rst
index 2ddf0b5..72b0cb9 100644
--- a/doc/source/cloner.rst
+++ b/doc/source/cloner.rst
@@ -61,6 +61,23 @@
 
 .. program-output:: zuul-cloner --help
 
+
+Ref lookup order
+''''''''''''''''
+
+The Zuul cloner will attempt to lookup references in this order:
+
+ 1) Zuul reference for the indicated branch
+ 2) Zuul reference for the master branch
+ 3) The tip of the indicated branch
+ 4) The tip of the master branch
+
+The "indicated branch" is one of the following:
+
+ A) The project-specific override branch (from project_branches arg)
+ B) The user specified branch (from the branch arg)
+ C) ZUUL_BRANCH (from the zuul_branch arg)
+
 Clone order
 -----------