I wish to publish a core originally based on someone else's work which is now however significantly different. The original author posted a notice allowing redistribution of the work or modified versions. Is it okay to publish at OpenCores.org ?

A couple caveats before attempting to answer:

• I am not a lawyer.
• I do not speak for OpenCores. I neither own, nor bear any part in the ownership of OpenCores.
• I can neither accept, nor assume, any liability for the advise I might offer below.
• My comments below are solely my own, based upon my own uneducated understanding of the law.

Caveats aside, if you are the legal owner of the work, then please feel free to post it. As I understand the definition of "legal owner", they are the ones with the established legal right to set the terms whereby the core may be used and copied by others.

If the work is already in the public domain under an OpenCores compatible license, then I would see no problems in (re)posting it under the same license. I think the owner would have problems if you chose to post it under "different" terms.

What I don't know is when a "derivative" work becomes a new work. I don't think I can help you there. My own notes on copyright law state that under the US Copyright Act of 1976 (as amended), the original owner has an exclusive right to prepare derivative works. I do not understand how that applies to open source "stuff", but I'd love to hear an answer if someone else might know it.

At this point, I might suggest that if the answer is still unclear, perhaps you should contact the owner of the original work upon which yours is based and discuss the issue further.

Just my two cents,

Dan