The designation is used for players who either tested positive for COVID-19 or had close contact with a person who has the coronavirus.
The NFL Players Association said Tuesday it had registered 21 positive tests so far.
NBC Sports' Peter King laid out the procedure for players who tested positive:
"If he has symptoms of COVID-19, at least 10 days must pass since the first symptoms occurred and at least 72 hours have passed since symptoms last occurred. He must test negative and have his return approved by a team doctor in consultation with league medical officials.
"If he is asymptomatic, 10 days must have passed since his positive test—or five days have passed since the positive test, plus two tests that show negative results, for him to resume playing."
Pro Football Talk's Josh Alper noted that players who weren't flagged for a positive test but had close contact with somebody infected need to pass only two tests over a period of more than 24 hours.
Golladay was the Lions' leading receiver in 2019, catching 65 passes for 1,190 yards and 11 touchdowns. Hockenson had a somewhat underwhelming rookie year, finishing with 32 receptions for 367 yards and two touchdowns in 12 games.