30mm RARDEN APSE info needed

I have a question about a British 30mm RARDEN APSE (Armor Piercing Secondary Effect) cartridge - black projectile with a green band (L5A1).

What exactly is the secondary effect? Is it explosive, incendiary, or something else? Does anyone know of a good reference on this round?

Thanks in advance!

The secondary effect is smoke. The projectile contains “oiled amorphous phosphorus”.

For reference see Labbett’s pamphlet on the 30x170 ammunition.

Here the diagram from Labbett:

APSE

Thinking over this I wonder if this would qualify as chemical ammunition and could be subject to international regulations/treaties.

Thanks for the info! I understand that at least in the US it would just be considered smoke.

In general yes but here the purpose is clearly against personnel and this is what could be questioned.