Add some more labels for logical addressing.

Doc/lib/libtypes.tex

@@ -662,6 +662,7 @@ source string) to the \code{exec} statement or the built-in
 See the \emph{Python Reference Manual} for more information.
 
 \subsubsection{Type Objects}
+\label{bltin-type-objects}
 
 Type objects represent the various object types.  An object's type is
 accessed by the built-in function \code{type()}.  There are no special
@@ -673,6 +674,7 @@ for all standard built-in types.
 Types are written like this: \code{<type 'int'>}.
 
 \subsubsection{The Null Object}
+\label{bltin-null-object}
 
 This object is returned by functions that don't explicitly return a
 value.  It supports no special operations.  There is exactly one null
@@ -681,6 +683,7 @@ object, named \code{None} (a built-in name).
 It is written as \code{None}.
 
 \subsubsection{File Objects}
+\label{bltin-file-objects}
 
 File objects are implemented using \C{}'s \code{stdio} package and can be
 created with the built-in function \code{open()} described under

Doc/libtypes.tex

@@ -662,6 +662,7 @@ source string) to the \code{exec} statement or the built-in
 See the \emph{Python Reference Manual} for more information.
 
 \subsubsection{Type Objects}
+\label{bltin-type-objects}
 
 Type objects represent the various object types.  An object's type is
 accessed by the built-in function \code{type()}.  There are no special
@@ -673,6 +674,7 @@ for all standard built-in types.
 Types are written like this: \code{<type 'int'>}.
 
 \subsubsection{The Null Object}
+\label{bltin-null-object}
 
 This object is returned by functions that don't explicitly return a
 value.  It supports no special operations.  There is exactly one null
@@ -681,6 +683,7 @@ object, named \code{None} (a built-in name).
 It is written as \code{None}.
 
 \subsubsection{File Objects}
+\label{bltin-file-objects}
 
 File objects are implemented using \C{}'s \code{stdio} package and can be
 created with the built-in function \code{open()} described under