Microware Systems will appeal against the US District Court ruling that lets Apple continue using Microware's registered trademark OS 9.

Microware said it received federal trademark registration for OS 9 in 1989, and was subsequently granted "incontestable status" for the registration. Apple didn't start using "Mac OS 9" until last year, according to Microware.

The Des Moines, Iowa-based embedded operating system vendor sued Apple in September last year over the alleged trademark infringement. A summary judgment last week dismissed Microware's claim under the "fair use" doctrine.

"Fair use permits others to use a protected trademark to describe aspects of their own goods, provided the use is in good faith and not as a trademark," US District Judge Robert Pratt wrote in his March 17 ruling.

Microware's OS 9 is the trademark for the company's real-time embedded operating system software licensed to equipment manufacturers and used to run cellular telephones and other wireless communications devices. Apple's Mac OS 9 is the latest release of the vendor's Macintosh desktop operating system.

The Judge said there was little chance consumers would mistake one product for the other because the operating systems are sold in different markets.