Alright, thanks for the answers, Andy and all,
This I what I suspected, I came across the idea of the unit class link shortly after I posted the question, I had been so deep into tweaking the weapons that I couldn't see that far anymore...
That was just to know if there was some workaround to have tanks firing APers cluster rounds (I know that IMI has been doing one for the Merkava, and there should be some more around). The answer being no.
Now while I'm on it, may I ask how the "cluster" class weapons are parametered in terms of effects?
I guess that like for all other weapons the accuracy is, basically speaking, the chance to hit something (so the one rating to improve when you have several submunitions around), both penetrations are clear enough, now what will be the role of the HEK (and APK respectively)? Does it only influence the amount of damage dealt on unarmored targets? Or has it some more specific link to the "spread" of the weapon, i.e. how many bullets in the cluster?
Like, f.e., can I put a nearly null HEK to weapons releasing "smart" AT seekers or would it have an impact on the overall effect?
Sorry for consistently asking such questions, but I can't run the game right now so I cannot run tests either.