diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index c196d3b..b7f9869 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -1,4 +1,4 @@
-*options.txt*	For Vim version 8.0.  Last change: 2018 Apr 18
+*options.txt*	For Vim version 8.0.  Last change: 2018 Apr 21
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -7444,7 +7444,9 @@
 	a S   Argument list status as in default title.  ({current} of {max})
 	      Empty if the argument file count is zero or one.
 	{ NF  Evaluate expression between '%{' and '}' and substitute result.
-	      Note that there is no '%' before the closing '}'.
+	      Note that there is no '%' before the closing '}'.  The
+	      expression cannot contain a '}' character, call a function to
+	      work around that.
 	( -   Start of item group.  Can be used for setting the width and
 	      alignment of a section.  Must be followed by %) somewhere.
 	) -   End of item group.  No width fields allowed.