The position number layout for all CBN polymer series issues is pretty basic. Here is what the position numbers on the
face of a sheet looks like:
01 | 11 | 21 | 31 | 41 |
02 | 12 | 22 | 32 | 42 |
03 | 13 | 23 | 33 | 43 |
04 | 14 | 24 | 34 | 44 |
05 | 15 | 25 | 35 | 45 |
06 | 16 | 26 | 36 | 46 |
07 | 17 | 27 | 37 | 47 |
08 | 18 | 28 | 38 | 48 |
09 | 19 | 29 | 39 | 49 |
Here is what the position numbers on the
back of a sheet looks like:
41 | 31 | 21 | 11 | 01 |
42 | 32 | 22 | 12 | 02 |
43 | 33 | 23 | 13 | 03 |
44 | 34 | 24 | 14 | 04 |
45 | 35 | 25 | 15 | 05 |
46 | 36 | 26 | 16 | 06 |
47 | 37 | 27 | 17 | 07 |
48 | 38 | 28 | 18 | 08 |
49 | 39 | 29 | 19 | 09 |
Notice that no position numbers end in a zero (0). This has the interesting effect of having all positions in a row ending with the same number, and that number corresponds to the row number. For instance, in row 1, the position numbers are 01, 11, 21, 31, and 41. When viewed from the front of the sheet, the position numbers rise from left to right. When viewed from the back, the PNs descend from left to right. Every note on the sheet has the same position number on the face and the back.
The physical layout never changes. What does change is the numbering patterns of serial numbers. Throughout the Journey series and starting into the polymer series, CBN numbered notes in columns, meaning the serial numbers would rise down one column, then go to the next column and continue. For the first 9 prefixes of the $20 polymer series (FIL-FIV), numbering was in rows, going from left to right as seen on the back of the printed sheet. That means the chronology of position numbers is as follows: 41, 31, 21, 11, 01, 42, 32, 22, 12, 02, 43, 33, ... , 49, 39, 29, 19, 09. This pattern harkens back to the days of the Bird series, with a couple of significant differences.
Unlike the Bird series notes that were skip-numbered by 500, sheets with prefixes FIL-FIV were skip-numbered by 1,000. Until now, CBN has never been known to use a split layout like their counterparts at BAI. Splitting the layout allows for two serial number ranges to be printed on the same sheet. The ninth and final row of the layout is where prefix FIV was printed. All notes with prefix FIV have position numbers ending in 9. The first eight rows of the layout were used to print the other eight prefixes. So at a skip-interval of 1,000, the first 40 positions of the layout created reams of 40,000 notes for prefixes FIL-FIU, while in the bottom row, reams of 5,000 notes were being made with prefix FIV. At 10,000,000 notes per prefix, that's 250 reams per prefix for FIL-FIU, for a total of 2,000 reams over 8 prefixes. Not coincidentally, when the 10,000,000 notes for prefix FIV are divided by 5,000 notes per ream, that means there are 2,000 "mini reams" of FIV notes.
Clearly, CBN planned the printing of the first ninety million $20 notes in a manner that allowed for two different prefixes to be printed on each and every sheet. This technique was used previously by BAI, but the pattern of serial number offsets (the so-called "mega-sequences") was no greater than 32 reams. CBN showed us that a pattern of offsets can be used over a much larger range which, in this case, is 2,000 reams.
What is not known at this time is whether CBN printed 1,000 sheets at a time or whether they were capable of keeping the numbering machines rolling for much longer runs. Why do I ask this question? Well, for one, CBN printed almost all of their Journey series notes with a skip-interval of 8,000, meaning that they could print 8,000 sheets at a time before the machine needed to be reset for the next batch. Switching to a smaller skip interval would mean the machine would have to stop and be reset more frequently. That's a distinct possibility if the printers wanted to be very careful to not make mistakes since polymer sheets with dozens of security features are very expensive and should not be wasted. However, the newest issues of CBN-printed polymer notes seem to be universally skip-numbered by 200. That is another subject for another discussion that I hope to post very soon.