Delta and US Airways passengers will see "TSA Prechk" on their paper boarding passes and the TSA PreCheck logo on mobile boarding passes. United fliers will see the PreCheck logo on both paper and mobile boarding passes.
The TSA advised that some types of boarding passes, such as those stored in Apple's Passbook feature, may not support the notification feature at this time.
(Read More: Apple: Swipe Your iPhone 5 'Passbook')
Also, the identifier will still print on boarding passes even if the airport a traveler is departing from doesn't have dedicated PreCheck lanes. To help avoid confusion in this case, the TSA advised checking the list of participating airports, which is updated frequently.
How PreCheck Works
If the TSA determines a passenger is eligible for expedited screening, information is embedded in the barcode of the passenger's boarding pass. The TSA officers scan the boarding pass at the document checking station to verify PreCheck status.
While passengers with the new printed indicator have been pre-cleared to access the dedicated PreCheck lane, no passenger is ever guaranteed expedited screening. The TSA continues to incorporate random, unpredictable screening measures.
Once past the ID check, travelers are generally able to leave shoes, belts and light outerwear on, as well as keep their laptops and approved liquids in their cases.
(Read More: Airports to Remove Invasive X-Ray Body Scanners)
More than 7.5 million passengers have received expedited screening through PreCheck since the initiative began in October 2011, according to the TSA. For more information on the new boarding pass feature, click here.