What does "clean language filter" means while creating an alliance?

[Jericho]

I'm curious about the definition of the clean language filter in both alliance search and creation. Can someone explain this?

Thanks

 

[dexterouz]

As far as i can understand its to avoid those alliances which might use offensive words; more of slang words
I don't care much about alliance using clean language. I am ok with any of the alliance