diff --git a/Doc/lib/libfuncs.tex b/Doc/lib/libfuncs.tex
index f195740418c..df384af41e9 100644
--- a/Doc/lib/libfuncs.tex
+++ b/Doc/lib/libfuncs.tex
@@ -434,18 +434,23 @@ one argument, return the smallest of the arguments.
   ignored).  If the file cannot be opened, \exception{IOError} is
   raised.
 
-If \var{mode} is omitted, it defaults to \code{'r'}.
-The optional \var{bufsize} argument specifies the file's desired
-buffer size: 0 means unbuffered, 1 means line buffered, any other
-positive value means use a buffer of (approximately) that size.  A
-negative \var{bufsize} means to use the system default, which is
-usually line buffered for for tty devices and fully buffered for other
-files.  If omitted, the system default is used.%
-\footnote{Specifying a buffer size currently has no effect on systems
-that don't have \cfunction{setvbuf()}.  The interface to specify the buffer
-size is not done using a method that calls \cfunction{setvbuf()}, because
-that may dump core when called after any I/O has been performed, and
-there's no reliable way to determine whether this is the case.}
+  If \var{mode} is omitted, it defaults to \code{'r'}.  When opening a 
+  binary file, you should append \code{'b'} to the \var{mode} value
+  for improved portability.  (It's useful even on systems which don't
+  treat binary and text files differently, where it serves as
+  documentation.)  The optional \var{bufsize} argument specifies the
+  file's desired buffer size: 0 means unbuffered, 1 means line
+  buffered, any other positive value means use a buffer of
+  (approximately) that size.  A negative \var{bufsize} means to use
+  the system default, which is usually line buffered for for tty
+  devices and fully buffered for other files.  If omitted, the system
+  default is used.\footnote{
+    Specifying a buffer size currently has no effect on systems that
+    don't have \cfunction{setvbuf()}.  The interface to specify the
+    buffer size is not done using a method that calls
+    \cfunction{setvbuf()}, because that may dump core when called
+    after any I/O has been performed, and there's no reliable way to
+    determine whether this is the case.}
 \end{funcdesc}
 
 \begin{funcdesc}{ord}{c}
@@ -649,10 +654,10 @@ local symbol table.  With a module, class or class instance object as
 argument (or anything else that has a \member{__dict__} attribute),
 returns a dictionary corresponding to the object's symbol table.
 The returned dictionary should not be modified: the effects on the
-corresponding symbol table are undefined.%
-\footnote{In the current implementation, local variable bindings
-cannot normally be affected this way, but variables retrieved from
-other scopes (e.g. modules) can be.  This may change.}
+corresponding symbol table are undefined.\footnote{
+  In the current implementation, local variable bindings cannot
+  normally be affected this way, but variables retrieved from 
+  other scopes (e.g. modules) can be.  This may change.}
 \end{funcdesc}
 
 \begin{funcdesc}{xrange}{\optional{start,} stop\optional{, step}}