Monster definition: special flag needed

Hi all!
I'm working on a monster definition with the DECORATE lump (ZDoom).
Now I'm searching for a flag that prevents an actor being damaged by the weapons of other actors of its kind. Like the Imp's fireballs never seem to damage other Imps.
Can't find this flag in the Wiki.
Do you remember it?

Thanks,

Marky.

I think (from editing in EDGE which is a totally different port, but there you go), it is automatic, in fact there is probably a special flag to make it NOT happen, but by default it does

(Though this is only for fireballs, bullets hurt anything they hit)

As deathbringer said:
For projectiles it is automatic, for hitscan weapons and melee attacks not possible - the same as it always had been in Doom.

There are no flags to change that behavior.

ok. thank you!

marky

deathbringer said:

I think (from editing in EDGE which is a totally different port, but there you go), it is automatic, in fact there is probably a special flag to make it NOT happen, but by default it does

(Though this is only for fireballs, bullets hurt anything they hit)

FWIW, The DDF flag that required to cause damaging from an attack used by given creature is ATTACK_HURTS.