What is PCBANG in 4S source code?

[brikara]

Hello guys, I was just messing a bit with 4S source code to get to know the game better and I am stuck at understanding one part. I saw PCBANG being mentioned in a lot of source code files, for example in this part of "TServer/TMapSvr/TMapSvr.cpp" file, I am not sure what is PCBANG? I tried looking at other files, but couldn't find out when is player in Pcbang and what is meant by it?

... 7729 line of TServer/TMapSvr/TMapSvr.cpp
case PROB_UPGRADE:        
{            
       wAddProb += bBaseProb * m_wEventValue[EVENT_ITEMUPGRADE] / 100;
       WORD wAdd = pPlayer->HaveItemProbBuff(SDT_STATUS_ITEMUPGRADE);            
       if(wAdd)            
       {
                wAdd Prob += bBaseProb * wAdd / 100;
                pPlayer->EraseItemProbBuff(SDT_STATUS_ITEMUPGRADE);
            }
            if(pPlayer->m_bInPcBang & PCBANG_REAL)
                wAddProb += bBaseProb;
        }
        break;
...

I was looking at the version on this GitHub page:

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Thanks in advance!