Questions about siggies ...sorta

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My questions is:
when someone is listing snakes or other pets and they put
1.0 copperhead rattlesnake
0.1 goldfish piranha
1.1 hamster Guinea pig

what does all that mean?

I have an idea but I have never been to a forum where this system is used so I just need a little clarification. Thank you!

I couldn't resist the animal names I am still giggling about the copperhead rattlesnake article

1.0 Male copperhead rattlesnake masupial
0.1 Female Goldfish Piranha
1.1 Male and Female Hampster Guinea Pig
4.4.8 Four Male Horse Sheep, Four Female Horse Sheep, and Eight unknown sex Horse Sheep.