Âdding new ItemGroups and ProbGroups

Hi,
i was wodering where are the Items of the _RefDropClassSel tables defined. For example in _RefDropClassSelRareEquip you can define the rarity of SOX Items. Each Degree (SoS/Moon/Sun) has its own ProbGroup. But where is it defined that ProbGroup xy has item x item y and item z? Or is it hard coded in the server files?
Would be nice if someone has a solution, i would like to create my own ItemGroups. Also it seem like Roc has its own ItemGroups. How does that work? Is it possible to give another unique like LordYarkan a Custom Made ItemGroup or is he only affected by the already existing _RefDropClasSel tables in Monster lvl80 row?

Thank you for your help :)

You might wanna take a look at _RefMonster_AssignedItemRndDrop && _RefDropItemGroup,
with combination of both tables, Yes, You should be able to create a customized drop for each mob unique or whatever.

hard coded at gameserver already reach it and created custom groups

Oh ok thank you gonna try it out, i will let you know