diff --git a/devtools/client/locales/en-US/sourceeditor.properties b/devtools/client/locales/en-US/sourceeditor.properties
index 01447e39cfd7..2c67fb514046 100644
--- a/devtools/client/locales/en-US/sourceeditor.properties
+++ b/devtools/client/locales/en-US/sourceeditor.properties
@@ -84,20 +84,28 @@ indentLess.commandkey=[
 # DO NOT translate this key without proper synchronization with toolbox.dtd.
 indentMore.commandkey=]
 
-# LOCALIZATION NOTE  (moveLineUp.commandkey): This is the key to use to move
-# the selected lines up.
+# LOCALIZATION NOTE  (moveLineUp.commandkey): This is the combination of keys
+# used to move the current line up.
+# Do not localize "Alt", "Up", or change the format of the string. These are key
+# identifiers, not messages displayed to the user.
 moveLineUp.commandkey=Alt-Up
 
-# LOCALIZATION NOTE  (moveLineDown.commandkey): This is the key to use to move
-# the selected lines down.
+# LOCALIZATION NOTE  (moveLineDown.commandkey): This is the combination of keys
+# used to move the current line up.
+# Do not localize "Alt", "Down", or change the format of the string. These are
+# key identifiers, not messages displayed to the user.
 moveLineDown.commandkey=Alt-Down
 
-# LOCALIZATION NOTE  (autocomplete.commandkey): This is the key to use
-# in conjunction with Ctrl for autocompletion.
+# LOCALIZATION NOTE  (autocompletion.commandkey): This is the key, used with
+# Ctrl, for code autocompletion.
+# Do not localize "Space", it's the key identifier, not a message displayed to
+# the user.
 autocompletion.commandkey=Space
 
-# LOCALIZATION NOTE  (showInformation2.commandkey): This is the key to use to
-# show more information, like type inference.
+# LOCALIZATION NOTE  (showInformation2.commandkey): This is the combination of
+# keys used to display more information, like type inference.
+# Do not localize "Shift", "Ctrl", "Space", or change the format of the string.
+# These are key identifiers, not messages displayed to the user.
 showInformation2.commandkey=Shift-Ctrl-Space
 
 # LOCALIZATION NOTE  (find.commandkey): This is the key to use in