IIRC it means they wont have pets with the POISONOUS creature class that also have the MAMMAL creature class. The latter means they wont use any of the pets as mounts, even if the creature normally does have a mount token.
I guess what I am asking is: are there currently any creatures in game with the POISONOUS creature class and the MAMMAL creature class? Do any POISONOUS creature class creatures have the MOUNT tag? If not, I assume that removing these wouldn't do anything. And if that is the case, does anyone know why they are there?
I ask because I am thinking about removing them for a mod.
You can remove them autonomously using creature variation templates for derived creatures like adder people etc which also have the POISONOUS class or add new ones in, you might still have to hunt down individual creatures in file though. I did a complete clean out of elves and this is what i got.
[CREATURE_VARIATION:ANIMAL_PERSON]
// convert tags for demonstration purposes, its best to leave ANIMAL_PERSON as intact as possible for ease of use
[CV_CONVERT_TAG]
[CVCT_MASTER:ANIMAL_CLASS]
[CVCT_TARGET:MAMMAL]
[CVCT_REPLACEMENT:ANIMAL_PERSON] // <- Relevant to making animalpeople exclusive, so mammalian animal people themselves are not used
[CV_CONVERT_TAG]
[CVCT_MASTER:ANIMAL_CLASS]
[CVCT_TARGET:REPTILE]
[CVCT_REPLACEMENT:ANIMAL_PERSON]
[CV_CONVERT_TAG]
[CVCT_MASTER:ANIMAL_CLASS]
[CVCT_TARGET:POISONOUS]
[CVCT_REPLACEMENT:ANIMAL_PERSON]
[ANIMAL]
[ANIMAL_CLASS:GOOD_PET]
[ANIMAL_CLASS:MAMMAL]
[ANIMAL_FORBIDDEN_CLASS:EVIL_PET]
[ANIMAL_FORBIDDEN_CLASS:ANIMAL_PERSON]
[ANIMAL_FORBIDDEN_CLASS:INSECT]
[ANIMAL_ALWAYS_MOUNT]
[ANIMAL_NEVER_WAGON_PULLER]
[ANIMAL_ALWAYS_SIEGE]
[ANIMAL_ALWAYS_PET]
[ANIMAL_ALWAYS_PACK_ANIMAL]
[ANIMAL]
[ANIMAL_CLASS:REPTILE]
[ANIMAL_CLASS:POISONOUS]
[ANIMAL_NEVER_MOUNT]
[ANIMAL_ALWAYS_PET]
[ANIMAL_NEVER_PACK_ANIMAL]
[ANIMAL_ALWAYS_SIEGE]
[ANIMAL_NEVER_WAGON_PULLER]
I had to go through my file and allocate [REPTILE] (doesn't exist on file) and [INSECT] (ditto to former) manually like i said, and good/evil classes were ones also of my own making to flesh out other civs but now elves only bring mammals as primary and reptiles as secondary creatures and im really happy with the result (apart from places i occasionally missed)
A more on-topic shorthand explanation since i realise i went a bit over the top is that you can per civ disable the use of a function like mount without removing it at the creature level with ANIMAL -> Arguement [CREATURE_CLASS] or [CREATURE_TOKEN:*animal*] -> [CREATURE_NEVER_MOUNT]
For my elf example, i could in theory have cave crocodiles, or surface alligators, but elves would never ride them because the civ ANIMAL tokens forbid them to.