AN-4-98 to FN-4-98 series

This series has AN-4-98 to FN-4-98 printed in the lower right hand corner, followed by a series of letters always starting at "K"
then descending in sequence to "A".
Once "A" is reached, a series of numbers always starting at 0 (zero) then descending in sequence to 1 follows.
Earliest known date: 13 FEB 99.