Next time you get your boarding pass, there are two codes you need to look out for.

One is SSSS. Those four letters mean you better prepare for a longer check in time at security. It means you’ve been selected for additional secondary security screening.

Why? You may trigger a red flag if you’re flying on a one-way ticket or purchased your ticket within 24 hours of your scheduled flight.

The second code is “see agent.”

It means you might have purchased a basic economy ticket and your seat only gets assigned at the gate, or the airline might have substituted a smaller aircraft for flight and your original seat no longer exists. This might also mean your flight is oversold. Either way, don’t wait to get to the gate to see the agent.