Though the practical impact is impossible to gauge, their arguments have been making waves.
The first was Mark Pilgrim, who wrote free software for the Mac in the mid-1990s.
He is involved with various current open-source projects, was a certified Mac OS X trainer and has written about Web site accessibility and scripting.
In a post on his blog, Pilgrim wrote that though he has long been impressed by Apples hardware and software, he thought that the latter had grown less attractive and more "restrictive," leading him to seek alternatives.
Pilgrim wrote that he regretted that Apples software, including the operating system, was not open-source (Pilgrim has published software under the GNU GPL [General Public License]; the license states that software published under it includes the source code, which users can modify to their liking as long as they document the changes.)
He noted that most applications he uses are so open—"Why keep running them on an operating system that costs money and restricts my rights and my usage?"
Part of Mac OS X is already open-source.
Darwin, the Unix foundations of the operating system, is available under the APSL (Apple Public Source License), a free software license.
The APSL is not compatible with the GPL, however, because it does not force developers using it to release their software for free. And no other part of Mac OS X, from its user interface layer to the applications (and their file formats), is open source.
Pilgrims argument was that non-open software often ties user data to a proprietary file format.
In the case of something going wrong, even an experienced user may find it impossible to fix the problem.