BRUSSELS, Sept 19 (Reuters) - EU antitrust regulators

launched proceedings on Thursday to ensure that Apple ( AAPL )

complies with landmark rules requiring it to open up its closed

ecosystem to rivals or risk a possible hefty fine.

Under the so-called specification proceedings, the European

Commission will spell out what Apple ( AAPL ) has to do to abide by the

Digital Markets Act (DMA), which came into effect last year.

"Today is the first time we use specification proceedings

under the DMA to guide Apple ( AAPL ) towards effective compliance with

its interoperability obligations through constructive dialogue,"

EU antitrust chief Margrethe Vestager said in a statement.

The EU competition enforcer said the first proceeding

targets iOS connectivity features and functionalities for

smartwatches, headphones, virtual reality headsets and other

internet-connected devices.

"The Commission intends to specify how Apple ( AAPL ) will

provide effective interoperability with functionalities such as

notifications, device pairing and connectivity," it said.

The second proceeding concerns how Apple ( AAPL ) addresses

interoperability requests submitted by developers and third

parties for iOS and iPadOS. Both processes will be wrapped up

within six months.

"It is crucial that the request process is transparent,

timely, and fair so that all developers have an effective and

predictable path to interoperability and are enabled to

innovate," the Commission said.

Apple ( AAPL ) said it will continue to work constructively with the

Commission but also warned of the risks.

"Undermining the protections we've built over time would put

European consumers at risk, giving bad actors more ways to

access their devices and data," it said in a statement.