Check for the status.
1) CDG-LKO/(Any station beyond LKO) = ARP Availability say X
2) LKO/Any station just beyond LKO-DBRG/Any station enroute. = ARP Availability say Y.
Where you would see Y>>>X (Y much much greater than X)
Now CDG-LKO necessary should be RS, but due to high demand for ticket enroute, you would perhaps see CDG-Any station coming under GNWL.
Now all these berths "Y" are not used for reservation against "X".
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EX:- A-B-C-D-E-F
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Now A- any station GN
Say PQ starts from B
B-C/D is PQ
B/C/D-E/F would come under RL
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Now it so happens that due to some reason PQ is perhaps not directly present.
A-F=> 100 berths
A-E=>90
A-D=> 80
A-C=> 70
A-B=> 60
GN Quota consists of total 100 berths. All the enroute station are however given separate quota. (100-90/100-80/90-70 and so on)
B-C=> 300 berths
B-D=> 250 berths
Now if B-C is 300 berths, it means that the same 300 berths may remain occupied between A-B. But according to the assumption, station A-B is only 60. Hence 240 berths are not used during booking but is actually used to clear WL between A-B.
Hope, I could make it clear.