Update C++ docstrings for extended histentry

models/clopath_synapse.h

@@ -247,16 +247,17 @@ clopath_synapse< targetidentifierT >::send( Event& e, size_t t, const CommonSyna
   std::deque< histentry_extended >::iterator start;
   std::deque< histentry_extended >::iterator finish;
 
+  // facilitation due to postsynaptic activity since last pre-synaptic spike
+
   // For a new synapse, t_lastspike_ contains the point in time of the last
   // spike. So we initially read the
   // history(t_last_spike - dendritic_delay, ..., T_spike-dendritic_delay]
   // which increases the access counter for these entries.
-  // At registration, all entries' access counters of
-  // history[0, ..., t_last_spike - dendritic_delay] have been
-  // incremented by ArchivingNode::register_stdp_connection(). See bug #218 for
-  // details.
+
+  // Note that in the STDP synapse, this loop iterates over post spikes,
+  // whereas here we loop over continuous-time history entries (see
+  // histentry_extended).
   target->get_LTP_history( t_lastspike_ - dendritic_delay, t_spike - dendritic_delay, &start, &finish );
-  // facilitation due to postsynaptic activity since last pre-synaptic spike
   while ( start != finish )
   {
     const double minus_dt = t_lastspike_ - ( start->t_ + dendritic_delay );

nestkernel/histentry.h

@@ -40,13 +40,15 @@ class histentry
   double t_;              //!< point in time when spike occurred (in ms)
   double Kminus_;         //!< value of Kminus at that time
   double Kminus_triplet_; //!< value of triplet STDP Kminus at that time
-  size_t access_counter_; //! how often this entry was accessed (to enable removal, once read by all synapses which need it)
+  size_t
+    access_counter_; //! how often this entry was accessed (to enable removal, once read by all synapses which need it)
 };
 
 /**
  * Class to represent a single entry in the spiking history of the ClopathArchivingNode or the UrbanczikArchivingNode.
  *
- * These history entries typically represent continuously-evolving values in time, so history timestamps correspond to ``nest.biological_time`` in simulation resolution rather than times of spikes.
+ * These history entries typically represent continuously-evolving values in time, so history timestamps correspond to
+ * ``nest.biological_time`` in simulation resolution rather than times of spikes.
  */
 class histentry_extended
 {
@@ -55,7 +57,8 @@ class histentry_extended
 
   double t_; //!< point in time for the history entry spike occurred (in ms)
   double dw_;
-  size_t access_counter_;  //! how often this entry was accessed (to enable removal, once read by all synapses which need it)
+  size_t
+    access_counter_; //! how often this entry was accessed (to enable removal, once read by all synapses which need it)
 
   friend bool operator<( const histentry_extended he, double t );
 };