diff --git a/doc/emacs/sending.texi b/doc/emacs/sending.texi
index 7d9f4917929..937ee568a3a 100644
--- a/doc/emacs/sending.texi
+++ b/doc/emacs/sending.texi
@@ -676,9 +676,11 @@ using this.
   In this chapter we have described the usual Emacs mode for editing
 and sending mail---Message mode.  This is only one of several
 available modes.  Prior to Emacs 23.2, the default mode was Mail mode,
-which is similar to Message mode in many respects but lacks features
-such as MIME support.  Another available mode is MH-E
-(@pxref{Top,,MH-E,mh-e, The Emacs Interface to MH}).
+which is similar to Message mode in many respects but is less
+feature-rich; for example, it supports only basic MIME: it allows you
+to add attachments, but lacks more sophisticated MIME features.
+Another available mode is MH-E (@pxref{Top,,MH-E,mh-e, The Emacs
+Interface to MH}).
 
 @vindex mail-user-agent
 @findex define-mail-user-agent
diff --git a/doc/lispref/commands.texi b/doc/lispref/commands.texi
index ea6e84e3730..e743038a778 100644
--- a/doc/lispref/commands.texi
+++ b/doc/lispref/commands.texi
@@ -3763,7 +3763,10 @@ character as far as keyboard translation is concerned, but it has the
 same usual meaning.
 
   @xref{Translation Keymaps}, for mechanisms that translate event sequences
-at the level of @code{read-key-sequence}.
+at the level of @code{read-key-sequence}.  If you need to translate
+input events that are not characters (i.e., @code{characterp} returns
+@code{nil} for them), you must use the event translation mechanism
+described there.
 
 @node Invoking the Input Method
 @subsection Invoking the Input Method