footnote about keyword args
diff --git a/Doc/ref/ref5.tex b/Doc/ref/ref5.tex
index 00383ef..62cd9a7 100644
--- a/Doc/ref/ref5.tex
+++ b/Doc/ref/ref5.tex
@@ -318,7 +318,8 @@
 \index{call}
 
 A call calls a callable object (e.g. a function) with a possibly empty
-series of arguments:
+series of arguments:\footnote{The new syntax for keyword arguments is
+not yet documented in this manual.  See chapter 12 of the Tutorial.}
 \obindex{callable}
 
 \begin{verbatim}