1 files changed, 1 insertions, 0 deletions

diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index 7108520e79f..b825b1d790b 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -4236,6 +4236,7 @@ A marker represents a buffer position to jump to.
 A string is text saved in the register.
 
 @item a rectangle
+@cindex rectangle, as contents of a register
 A rectangle is represented by a list of strings.
 
 @item @code{(@var{window-configuration} @var{position})}