--- a/runtime/doc/map.txt
+++ b/runtime/doc/map.txt
@@ -1,4 +1,4 @@
-*map.txt*       For Vim version 8.2.  Last change: 2021 Mar 17
+*map.txt*       For Vim version 8.2.  Last change: 2021 Apr 23
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -244,9 +244,12 @@ have a look at |maparg()|.
 If the first argument to one of these commands is "<expr>" and it is used to
 define a new mapping or abbreviation, the argument is an expression.  The
 expression is evaluated to obtain the {rhs} that is used.  Example: >
-	:inoremap <expr> . InsertDot()
-The result of the InsertDot() function will be inserted.  It could check the
+	:inoremap <expr> . <SID>InsertDot()
+The result of the s:InsertDot() function will be inserted.  It could check the
 text before the cursor and start omni completion when some condition is met.
+Using a script-local function is preferred, to avoid polluting the global
+namespace.  Use <SID> in the RHS so that the script that the mapping was
+defined in can be found.
 
 For abbreviations |v:char| is set to the character that was typed to trigger
 the abbreviation.  You can use this to decide how to expand the {lhs}.  You
@@ -261,7 +264,7 @@ input. Example: >
 	  call popup_create(... arguments ...)
 	  return "\<Ignore>"
 	endfunc
-	nnoremap <expr> <F3> <Sid>OpenPopup()
+	nnoremap <expr> <F3> <SID>OpenPopup()
 
 Also, keep in mind that the expression may be evaluated when looking for
 typeahead, before the previous command has been executed.  For example: >