Forge - What does Groups [exclude] do?

I don’t understand this object filter at all, and several of the brains in the 343 game modes use it. They often will be filtering Objects and the first line will be THIS [include] followed by Groups [exclude]. I get that THIS is adding that object to the list, but I don’t understand the purpose of the second part or even what type of group its referring to. Are these physics groups, like for joints? Are they forge groups like you use when you want to move pieces around together?