Hello we are using RFA 8.1 C++ api's to consume market data. 
When I subscribe to "AA"  I get "FID[4] [IDN EXCHANGE ID] as NYQ"
When I subscribe to "AA.N"  I get "FID[4] [IDN EXCHANGE ID] as NYS"
May I know what is the difference between NYS and NYQ? 
What exchange "NYQ" represents?