Audience Targeting

Hello,

I have a question regarding Audience targeting in Target Standard.

When creating audience segments in an A/B test, say for example I am trying to segment by city.

The rule I will add is say, City matches NewYork. 

My question is what does the above rule mean? - Does this mean that campaign will be shown only to users when their city matches NewYork? If I want to exclude users from other cities from seeing my campaign, then should I also include City does not match Boston, Chicago etc along with the above rule?

Thanks...