AN-06-04 to FN-06-04 series

This series has AN-06-04 to FN-06-04 printed mid-way down the ticket towards left hand edge, followed by either a blank,
or a series of letters always starting at "I" then descending in sequence to "A".
Once "A" is reached, a series of numbers always starting at 9 then descending in sequence to 1 follows.
Earliest known date: 26 NOV 04.