Soon after the release of three alphabets prefix i.e. AAA by Bank Negara Malaysia (BNM) in 2010, the replacement notes have also followed with the three alphabets prefix i.e. ZAA. And recently, the ZAB replacement notes also release to the market.
There is an obvious discrepancy between the ZAA and ZAB. Noted that the font size used for ZAB is slightly bigger than ZAA. In ZAB replacement note, you will notice that the prefix font size is bigger than the first numeric font i.e. 'ZAB' has a bigger font size than '0'. However, you will not find this in ZAA replacement note.
3rd Series RM1 ZAB Replacement Note.