Firebird/Interbase license is mentioned on theserverside.com

"Several years ago, Borland released the Interbase Database source
code as an Open Source project. They then, quickly, turned around and
brought it back in house. Obviously, it was immediately forked and
today we have Firebird, which as far as I can tell is on a divergent
course from Interbase.

Interbase wasn't free long enough for any community work to have been
done on it before it was taken back, and I'm not familiar with their
license. But it is an example of a company "changing its mind"
regarding an open source project."

http://www.theserverside.com/news/thread.tss?thread_id=35242

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developer flamerobin.org