BRUSSELS, Sept 19 (Reuters) - EU antitrust regulators on

Thursday launched proceedings to ensure that Apple ( AAPL )

complies with landmark rules requiring it to open up its closed

ecosystem to rivals.

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.

"The first proceeding focuses on several iOS connectivity

features and functionalities, predominantly used for and by

connected devices," the EU competition enforcer said.

"The second proceeding focuses on the process Apple ( AAPL ) has set

up to address interoperability requests submitted by developers

and third parties for iOS and IPadOS," it said.