I agree with Dennis and Jim; however, maybe you ask about the name or location fields where separators for ( or ), and [ or ] are not allowed, among others.
In that case, maybe what you are trying to include isn't something that belongs in a field and is better explained in the Biography section narrative or Research Notes. Since your question doesn't provide a specific profile or situation, this is the best I can give.
Feel free to reach out with specific info if this doesn't answer your question.