Spell data missing stacking groupFollow

So, admittedly, I have no idea where this data is coming from in-game, but if I inspect a spell that has a stacking group it is clearly displayed in the inspect window. For example Tainted Breath has "Stacking Group: Blood of Saryrn" and "Stacking Group Rank: 1". Envenomed Breath also has "Stacking Group: Blood of Saryrn" but "Stacking Group Rank: 2". Venom of the Snake is also Blood of Saryrn, but rank 3. Since these are all in the same group, they can land on a mob once per caster and lower ranks will be blocked by higher ranks and higher ranks will overwrite lower ranks.

But Scorpion Venom has "Stacking Group: Scorpion Venom" and "Stacking Group Rank: 1" Even though it is Rank 1, it will not be overwritten by Venom of the Snake due to having different Stacking Groups.

I've looked into the raw spell data and I cannot find where stacking groups are. The only things I found that Tainted Breath, Envenomed Breath, and Venom of the Snake have in common that differs from Scorpion Venom are:
deletable (the first 3 can be deleted, Scorpion Venom cannot)
fizzle time (the first 3 are 1.5, Scorpion Venom is 3)
pvpresistbase (5 for the first 3, -87 for Scorpion Venom)
pvpresistcalc (101 for the first 3, 136 for Scorpion Venom)
allow_spellscribe (1 for the first 3, 5 for Scorpion Venom)

And none of these look like stacking groups and stacking group ranks. I guess this could be all handled server side and is potentially not data that can be parsed out f the spells txt, but it would be nice to know what stacking groups different spells belong to.