Mention the new file() builtin in the section on file objects.
diff --git a/Doc/lib/libstdtypes.tex b/Doc/lib/libstdtypes.tex
index 765ba94..f1684d3 100644
--- a/Doc/lib/libstdtypes.tex
+++ b/Doc/lib/libstdtypes.tex
@@ -1187,9 +1187,12 @@
\label{bltin-file-objects}}
File objects are implemented using C's \code{stdio} package and can be
-created with the built-in function
-\function{open()}\bifuncindex{open} described in section
-\ref{built-in-funcs}, ``Built-in Functions.'' They are also returned
+created with the built-in constructor
+\function{file()}\bifuncindex{file} described in section
+\ref{built-in-funcs}, ``Built-in Functions.''\footnote{\function{file()}
+is new in Python 2.2. The older built-in \function{open()} is an
+alias for \function{file()}.}
+They are also returned
by some other built-in functions and methods, such as
\function{os.popen()} and \function{os.fdopen()} and the
\method{makefile()} method of socket objects.