The Persian range seems to have had three groups each of five infantry figures (Immortals, Royal Guard and Medes).
The codes for the Immortal figures are:
AP1 Officer with axe
AP2 Standard bearer
AP3 Immortal firing bow
AP4 Immortal thrusting with spear
AP5 Immortal marching with spear
The marching pose seems to be different from those for the other two groups, which apper to be similar to the standard bearer but carryong a spear with a round sphere at the base. However, I may very well be wrong about this - any information by comment gratefuly received.
The picture shows four of these figures, the standard bearer being missing.