opt in something
opt into something

Any student may opt into these classes if they so wish.

Each room is also wired for phone services should the residents choose to opt into this service.

Since 2006 certain previously excluded workers can opt into the system on a voluntary basis.

"We want to know if students would actually try to fail to opt into the program to obtain the subsidy," he said.

Both states will be able to opt into these voting issues on a case-by-case basis.

Within this area, almost all children attend comprehensive schools, though it is still possible to opt into the Eleven plus system.

About 30 percent of the state's 811 districts opted into the program in 1999.

As you said, Leo, he's opting into specific cookies that he wants to allow.

He continued holding that post until his ally opted into another alliance in June 1995.

Permitted power generating plants may opt into the trading program.