[ns] Q2 about Nortel patch

["Zhang Guangming" <hometh@chinaren.com>]

hi there,
I am puzzled by some of the detail of
the dsredq.cc
In the file's function of 
int redQueue::enque(Packet *pkt, int prec, int ecn) 
   //if the avg is greater than the min threshold,
        ...
         //if avg queue isn't  greater than max. threshold
         u = Random::uniform(0.0, 1.0);
         //drop it
			if (u <= pa) {	
            if (ecn) return PKT_MARKED;  ???
            return PKT_EDROPPED;
         }
      } else { //if avg queue is greater than max. threshold
			qParam_[prec].edv_.count = 0;
         if (ecn) return PKT_MARKED;    
         return PKT_DROPPED;

then:
Can u help me to understand what's the difference
between PKT_MARKED,PKT_EDROPPEDand PKT_DROPPED
thx.