As best as I can make out, this is the format of a driver number in the UK, as it appears on a driving licence.
First five letters of your surname, padded on the right with nines if your surname is shorter than five letters. Date of birth, in the format YMMDDY. 50 is added to the month if you're a woman. Initials of first two forenames, or your first initial and a 9 if you only have one forename. Another 9. Two verification characters, computed from the rest of the number.
For example, John James Jenkins, born on the 1st of June 1975, might have a driver number of JENKI706015JJ9AB.
I get the surname and initials parts. At least that's vaguely logical, even if the choice of a 9 as a padding character is a bit arbitrary. But what the steaming monkey fluid were they thinking when they decided on the date of birth bit? What kind of calendrical malefactor puts the decade digit at one end and the year digit at the other, sandwiching the month and date in between? It's like writing twelve o'clock as 10:00:02.
The British do like to criticise the Americans' horribly misordered date format of month-day-year, but our friends from across the pond need only point out our driving licences to secure instant victory in any date format illogicality-based argument.
I can't find any information online as to the reason behind such a ridiculous way of writing a date, so if anyone reading this has any idea, theory, or even wild speculation about why it's done like this, do speak up.