9320 is the Unit Serial Number (USN). All units have them, and under the quadripartite STANAG arrangements, Units were required to display the USN and the colour-coded Christmas tree, but I heard recently that the requirement has now been dropped. The colours represent the numbers, and are exactly the same colour-number system used in the earlier, 3 stripe 'bar code' dating from before WW2:
1 Red
2 Blue
3 Yellow
4 Light Green
5 Grey
6 Buff
7 Red Oxide (Maroon/deep orange)
8 Service colour, ie Olive Drab/deep Brunswick Green
9 White
0 Brown
1 Armoured Regiment is 5228 - Grey-Blue-Blue-Green. Sorry I don't know the Unit for 9320. The majority of USNs during the SVN period were between 1 and 3 thousand (1000 to 3000), 3 Cav were 1125, for example. There is a late 1971 unit list and the marking instruction for the three-stripe system on page 298-299 of 'Mud and Dust'.
Mike C
