The serial number on Philippine banknotes consists of two (2) alpha and six numerics per denomination. The total number of banknotes per denomination that can be printed with SN A0000001 to SN ZZ1000000 is 600 million pieces. When the actual production of banknotes per denomination exceeds 600 million pieces, the suffix A is added after the year mark in order to avoid duplication of the serial number.”

Hi Aqamano, Thanks for your help working out what's going on with these "A" numbers. BUT, if the serial numbers run from A - ZZ (minus the I's and O's), that means after reaching 2008 "ZZ" we start again with 2008A "A". When we look at the 2008A notes we see the "A" prefix and prefix's down to "AR", then no 2008A prefix's until "XG". All I can ask is....Where are the 2008A notes in between "AR" and "XG"?