Should receive symbols in the subscription response mapping to the type (RT, DL, etc). If symbols are NA it most likely means the connection is not entitled to the exchange/market data. If the symbol is also found in the “invalid” list, it could mean the client is using invalid symbology or that the symbol has expired (but could still have historical data, news, etc).
If the symbol is found in the rejected list, the subscription count limit could have been reached.