--- a/mercurial/help/subrepos.txt	Thu Mar 21 18:27:09 2019 -0700
+++ b/mercurial/help/subrepos.txt	Thu Mar 21 21:40:22 2019 -0400
@@ -105,8 +105,10 @@
     Subversion subrepositories will print a warning and abort.
 
 :diff: diff does not recurse in subrepos unless -S/--subrepos is
-    specified. Changes are displayed as usual, on the subrepositories
-    elements. Subversion subrepositories are currently silently ignored.
+    specified.  However, if you specify the full path of a file or
+    directory in a subrepo, it will be diffed even without
+    -S/--subrepos being specified.  Subversion subrepositories are
+    currently silently ignored.
 
 :files: files does not recurse into subrepos unless -S/--subrepos is
     specified.  However, if you specify the full path of a file or