Apple seems to have learnt a few tricks from arch rival Microsoft with the news that an "update" to the iPod's software locks out music files from another rival, RealNetworks.

The change affects Apple's new iPod Photo, which lets users store and display their digital image collections in addition to digital music.

It also comes several months after it accused Real of adopting "the tactics and ethics of a hacker to break into the iPod." In July, Real announced a technology called Harmony that allows consumers to download songs they can play on a wide variety of portable digital media players, including Apple's iPod devices.

"As we stated in July, we strongly caution Real and their customers that when we update our iPod software from time to time it is highly likely that Real's Harmony technology will cease to work with current and future iPods," an Apple spokeswoman said yesterday.

Real hasn't taken kindly to Apple appearing to abuse its virtual monopoly thanks to the iPod's huge success. But it hid its menace in temperate terms. "Apple has made some changes to FairPlay," said spokesman Matt Graves. "It's not clear that they've done that specifically to break Harmony or just as a by-product."

No matter because Harmony will rise to the challenge and change Harmony to "restore compatibility" with the iPods. "Any time there are changes made to FairPlay we have to evaluate it to see how Harmony works with it," Graves said.

Seems that the IT industry will have to relearn the file format lesson all over again.

Additional reporting by Joris Evers, IDG News Service