Who says South India does not have Gatimaan. It is called Vaigai Express. - Thamizh Maran

#berthmultiplexing
I was asked by many of you if I could frame down the definition to the above term and the tiny little intrinsic details associated with the same in a single blog for easy reference. So, here it goes:
Imagine:
a) A train which follows the route HWH-BWN-DHN-MGS-CNB-NDLS.
b)...
more...

100 berths allocated for ARP Booking all the journey leg/s combined.
Now someone comes and books all the 100 berths for HWH-BWN. The availability status say enters RAC (RAC 1 being the current status).
Now again assume, someone else comes in and wants to book 10 tickets for BWN-DHN. He would get all his berths confirmed.
Confused? The status was at RAC 1. Isn't it?
Don't ponder over this again. It is very simple. Even though all the 100 berths were consumed up earlier, the booking was only till BWN leaving the rest of the portion vacant. So technically anyone can book 100 berths for BWN-NDLS or enroute.
This, precisely is #berthmultiplexing where a berth is split up into many parts and serves multiple passenger for multiple journey legs at the same time. (If anyone is familiar with the phrase "Multiplexing" in Computers, he can always relate these two).
This is one very important concept which forms the basis to almost all the phenomena that takes place in IR. What are those?
i) Confirmation through different quota.
ii) Splitting up various passengers in a single PNR into various quota for the same journey leg.
iii) #chartingatoriginatingstation
iv) #chartingatpreviousremotestation
So, when do we know that the berths are going to get forwarded? How does this happen actually? In what ways are the berths being used up?
Would answer to all these in my next post, once everyone is done understanding whatever is been written above.