Index: R/src/library/base/man/character.Rd
===================================================================
--- R/src/library/base/man/character.Rd	(revision 39730)
+++ R/src/library/base/man/character.Rd	(working copy)
@@ -34,6 +34,9 @@
   back to numeric may change the number.  If you want to convert numbers
   to character with the maximum possible precision, use
   \code{\link{format}}.
+
+  \code{as.character} replaces \code{NA} values from non-character modes
+  with the \code{character} \code{"NA"}, which is not \code{NA}.
 }
 \value{
   \code{character} creates a character vector of the specified length.