Union workers at Royal Dutch Shell's Pennsylvania petrochemical plant were given the option of attending President Trump's address there this week or miss out on wages, the Pittsburgh Post-Gazette first reported Saturday.

Details: A contractor relayed to employees that Shell sent union leaders a memo the day before Trump's visit Tuesday to the $6 billion construction site that attendance wasn't mandatory, but "only those who showed up at 7 a.m., scanned their ID cards, and prepared to stand for hours — through lunch but without lunch — would be paid," according to the news outlet.

"No yelling, shouting, protesting or anything viewed as resistance will be tolerated at the event," Shell instructed employees at the plant in Beaver County just outside Pittsburgh, the Pittsburgh Post-Gazette reports.

What they're saying: Shell spokesperson Curtis Smith told Newsweek that workers who chose to skip the rally received "paid time off," which doesn't count as hours worked and, therefore, doesn't qualify for overtime pay.

Another Shell spokesperson, Ray Fisher, said in a statement to the New York Times the event was treated as a training day for workers, "with a guest speaker who happened to be the president."

"It was understood some would choose not to attend the Presidential visit and were given the option to take paid time off. As with any workweek, if someone chooses to take PTO, they are not eligible to receive the maximum overtime available."

— Shell spokesperson Ray Fisher's statement to the NYT

The big picture: Trump's visit was attended by 5,000 workers, according to Newsweek.