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The 4-Letter Code You Do NOT Want To See On Your Boarding Pass

Getting throughairport security can take forever, butfour little letters on your boarding pass are a clue you’re in for even more screening.

Some passengers on flights within or bound for the U.S. may find “SSSS” printed on their boarding passes, Business Insider pointed out this week. That stands for “Secondary Security Screening Selection,” and it entails a10- to 30-minute additional screening that may involve a thorough search of your bags,a full-body pat down,questioning about your travel plans andadditional body scans. Unless something sketchy turns up,you’ll board as usualafter the screening.

The Transportation Security Administration’s Secure Flight program, which is currently responsible for that “SSSS” code, has been around since 2010and stems from laws passed after 9/11.Travelers report seeing the "SSSS" codeon their boarding passes years before that, so it's likely that another government program used the code earlier, according to TSA spokesman Mike England.

Today, the “SSSS” code is printed on travelers’ boarding passes if they appear on an FBIcounterterrorism watchlistcalled the Selectee List, England said. Others are assigned the “SSSS” code at random.

“Secure Flight is a risk-based passenger prescreening program that enhances security by identifying low and high-risk passengers before they arrive at the airport by matching their names against trusted traveler lists and watchlists,” England told HuffPost.

You may be more likely to wind up with the codeif you booked your flight last-minute, booked a one-way ticket or are returning from ahigh-risk country, travel expertBen Schlappig writes. Experienced flyerThe Points Guy noted he seemed to get the “SSSS” code on every airport visit after taking a trip to Turkey, for reasons unknown. 

It’s normal for travelers to get the “SSSS” codeevery once in a while, but if it happens frequently, you may be on a watchlist by mistake, Lifehacker notes.You can contact the government’sTraveler Redress Inquiry Programfor any issues related to screening delays and request a review, England said. 

Meanwhile, cross your fingers andread up on how to breeze through security with ease. 

CLARIFICATION: A previous version of this story said the “SSSS” code came into use in 2010. While that was when the TSA’s Secure Flight program began using the code, the TSA says another government program may have been using it before that, as travelers reported seeing it years earlier.

This article originally appeared on HuffPost.