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+ptr_lib (C++)
+=============
+
+Some C++ methods need to use shared_ptr. Depending on where ./configure found shared_ptr, define the ptr_lib namespace as follows, so that the API always uses ndn::ptr_lib::shared_ptr.
+
+.. code-block:: c++
+
+    #if NDN_CPP_HAVE_STD_SHARED_PTR
+    #include
+    #include <memory>
+    namespace ndn { namespace ptr_lib = std; }
+    #elif NDN_CPP_HAVE_BOOST_SHARED_PTR
+    #include <boost/shared_ptr.hpp>
+    #include <boost/make_shared.hpp>
+    namespace ndn { namespace ptr_lib = boost; }
+    #else
+    // Use the boost header files in this distribution.
+    #include <ndnboost/shared_ptr.hpp>
+    #include <ndnboost/make_shared.hpp>
+    namespace ndn { namespace ptr_lib = ndnboost; }
+    #endif
+
+Time representation
+===================
+
+Some methods use calendar time or a time interval.  These are represented as follows.
+
+Milliseconds Typedef
+--------------------
+
+(C++ only) A time interval represented as the number of milliseconds.
+
+:[C++]:
+    Namespace: `ndn`
+
+.. code-block:: c++
+
+    typedef double Milliseconds;
+
+MillisecondsSince1970 Typedef
+-----------------------------
+
+(C++ only) The calendar time represented as the number of milliseconds since 1/1/1970.
+
+:[C++]:
+    Namespace: ndn
+
+.. code-block:: c++
+
+    typedef double MillisecondsSince1970;