Heavy discussion going on !! :)
I also have not been able to understand the various quotas PQWL, RLWL, RSWL, etc.
You have said From A-B, A-C, A-D (GNWL) where A is starting station. Thuis may not always be true. Check /blog/post/88130
Train: 2909 BDTS NZM Garib Rath
From: Mumbai Bandra Terminus/BDTS
To: Mathura Junction/MTJ
Date of Journey: Tue Nov 30 @ 16:55
Class: AC 3-tier
Passenger 1: Waitlist# 17 (Booking Status: W/L 33, PQWL)
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Passenger 2: Waitlist# 18 (Booking Status: W/L 34, PQWL)
Passenger 3: Waitlist# 19 (Booking Status: W/L 35, PQWL)
Chart NOT Prepared

Hope the details given below clears bearth/Quota allocation and why BDTS-MJT got PQ.
2909 NZM GARIB RATH 02-12-2010 BANDRA TERMINUS MATHURA JN GENERAL


S.No. Date (DD-MM-YYYY) Class - 3A Class -CC
1 2-12-2010 Charting Done Charting Done
2 4-12-2010 REGRET/WL 30 WL 66/WL 45
3 7-12-2010 REGRET/WL 30 WL 20/WL 9
4 9-12-2010 REGRET/WL 31 WL 27/WL 21
5 11-12-2010 REGRET/WL 30 WL 27/WL 25
6 14-12-2010 REGRET/WL 30 AVAILABLE 41
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2909 NZM GARIB RATH 02-12-2010 BANDRA TERMINUS H NIZAMUDDIN GENERAL
S.No. Date (DD-MM-YYYY) Class - 3A Class -CC
1 2-12-2010 Charting Done Charting Done
2 4-12-2010 WL 620/WL 273 WL 71/WL 31
3 7-12-2010 WL 452/WL 253 WL 37/WL 25
4 9-12-2010 WL 454/WL 287 WL 39/WL 29
5 11-12-2010 WL 458/WL 287 WL 56/WL 42
6 14-12-2010 WL 350/WL 252 AVAILABLE 64
2909 NZM GARIB RATH 02-12-2010 BANDRA TERMINUS SURAT GENERAL
S.No. Date (DD-MM-YYYY) Class - 3A Class -CC
1 2-12-2010 Charting Done Charting Done
2 4-12-2010 REGRET/WL 30 WL 66/WL 45
3 7-12-2010 AVAILABLE 42 AVAILABLE 1
4 9-12-2010 REGRET/WL 31 WL 27/WL 21
5 11-12-2010 REGRET/WL 30 WL 27/WL 25
2909 NZM GARIB RATH 02-12-2010 SURAT MATHURA JN GENERAL
S.No. Date (DD-MM-YYYY) Class - 3A Class -CC
1 2-12-2010 Charting Done Charting Done
2 4-12-2010 WL 84/WL 29 WL 31/WL 22
3 7-12-2010 WL 50/WL 30 WL 6/WL 4
4 9-12-2010 WL 68/WL 55 WL 11/WL 8
5 11-12-2010 WL 51/WL 37 WL 11/WL 11
6 14-12-2010 WL 42/WL 32 AVAILABLE 41

I had also mentioned
If ticket is purchased from B or C (for journey from B-C-D or A-B-C-D, and if B or C are imp places then the ticket wud be in RL (Note: Journey here can be also from A to any station).
A-B-C-D (GNWL/RLGN) depending on where the ticket is purchased
According to a blogger above,
PQWL will also get confirmation against Bookings under General Quota, if they can fit in that bookings.
In this case, clearly the train is in demand (for tickets to be issued in PQWL).
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Ticket has been purchased from Mathura. It might be that it shares a PQ with Mumbai and hence PQWL or it was purchased from Mumbai, where GNWL was already running high in WL, hence they accommodated this ticket in PQ!

anatomy of this trains quota is given below(remember what advice i have given )
6317 HIMSAGAR EXP 03-12-2010 ERNAKULAM TOWN TIRUPATI GENERAL
S.No. Date (DD-MM-YYYY) Class - 3A Class -SL
1 3-12-2010 REGRET/WL 10 WL 71/WL 45
2 10-12-2010 REGRET/WL 11 REGRET/WL 59
3 17-12-2010 REGRET/WL 11 REGRET/WL 50
4 24-12-2010 REGRET/WL 10 REGRET/WL 50
5 31-12-2010 REGRET/WL 10 REGRET/WL 53
6 7- 1-2011 REGRET/WL 10 WL 65/WL 26
6317 HIMSAGAR EXP 03-12-2010 KANYAKUMARI ERNAKULAM TOWN GENERAL
S.No. Date (DD-MM-YYYY) Class - 3A Class -SL
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1 3-12-2010 WL 62/WL 18 AVAILABLE 31
2 10-12-2010 WL 48/WL 27 AVAILABLE 53
3 17-12-2010 AVAILABLE 1 AVAILABLE 49
4 24-12-2010 WL 52/WL 37 AVAILABLE 30
5 31-12-2010 AVAILABLE 2 AVAILABLE 30
6 7- 1-2011 WL 35/WL 23 AVAILABLE 51
6317 HIMSAGAR EXP 03-12-2010 KANYAKUMARI TIRUPATI GENERAL
S.No. Date (DD-MM-YYYY) Class - 3A Class -SL
1 3-12-2010 WL 62/WL 18 WL 253/WL 95
2 10-12-2010 WL 48/WL 27 WL 199/WL 121
3 17-12-2010 WL 45/WL 19 WL 125/WL 99
4 24-12-2010 WL 52/WL 37 WL 233/WL 166
5 31-12-2010 WL 64/WL 46 WL 154/WL 117
6 7- 1-2011 WL 35/WL 23 WL 177/WL 142
6317 HIMSAGAR EXP 03-12-2010 KANYAKUMARI VIJAYAWADA JN GENERAL


S.No. Date (DD-MM-YYYY) Class - 3A Class -SL
1 3-12-2010 WL 62/WL 18 WL 253/WL 95
2 10-12-2010 WL 48/WL 27 WL 199/WL 121
3 17-12-2010 WL 45/WL 19 WL 125/WL 99
4 24-12-2010 WL 52/WL 37 WL 233/WL 166
5 31-12-2010 WL 64/WL 46 WL 154/WL 117
6 7- 1-2011 WL 35/WL 23 WL 177/WL 142
***the ERS limited quota extends up to BZA and beyond. Hence PQ.
6317 HIMSAGAR EXP 03-12-2010 ERNAKULAM TOWN NEW DELHI GENERAL
S.No. Date (DD-MM-YYYY) Class - 3A Class -SL
1 3-12-2010 REGRET/WL 10 WL 71/WL 45
2 10-12-2010 REGRET/WL 11 REGRET/WL 59
3 17-12-2010 REGRET/WL 11 REGRET/WL 50
4 24-12-2010 REGRET/WL 10 REGRET/WL 50
5 31-12-2010 REGRET/WL 10 REGRET/WL 53
6 7- 1-2011 REGRET/WL 10 WL 65/WL 26
Clearly a common man can not search like this (even we too)so getting PQ is not a surprising matter.