diff --git a/runtime/doc/if_tcl.txt b/runtime/doc/if_tcl.txt
index f7c0d6f..60ac6bc 100644
--- a/runtime/doc/if_tcl.txt
+++ b/runtime/doc/if_tcl.txt
@@ -30,7 +30,7 @@
 			is working: >
 				:tcl puts "Hello"
 
-:[range]tc[l] << [endmarker]
+:[range]tc[l] << [trim] [{endmarker}]
 {script}
 {endmarker}
 			Execute Tcl script {script}.
@@ -38,10 +38,9 @@
 			wasn't compiled in.  To avoid errors, see
 			|script-here|.
 
-The {endmarker} after {script} must NOT be preceded by any white space.
-
 If [endmarker] is omitted from after the "<<", a dot '.' must be used after
-{script}, like for the |:append| and |:insert| commands.
+{script}, like for the |:append| and |:insert| commands.  Refer to
+|:let-heredoc| for more information.
 
 This form of the |:tcl| command is mainly useful for including tcl code in Vim
 scripts.