I still have some questions about the BSD License usage

Question

Let's say I'm doing this application where I include some class I found on the web with the BSD License attached. I know that this license allows me to modify the code and I have the need for it.

Now, the BSD license states the year and the copyright holder name, let's say we are talking about some piece of code written by John Doe.

1) If I release my whole application source code with the my modifications to John Doe's class which copy of the BSD License should I attach to class source code file? The one with my own year and name, the one with John Doe's year and name Both?

Or maybe the one with my name and year since that specific code revision was by me but also leave a copyright notice saying that the original code is copyrighted by John Doe? This one seems the right choice, is it?

2) Now let's imagine that I don't want to use the BSD License for the rest of my application (I know I have to use it at least for the John Doe's class modification) and instead, I want to use the MIT License.

If we are talking about source code files as above, I think it's pretty easy, I just attach the MIT License to all code files completely written by me and as for John Doe's modified class, I just use the proper BSD License as per the right answer to #1 from you guys.

However, it's always nice to attach the licenses in text files (LICENSE.txt for instance) too when distributing the packaged source code. Should I attach two license text files or what would you guys suggest?

Answer 1

My advice would be to find a lawyer that specialized in open source licensing issues. Real legal advice is worth it in this case.

Perhaps a web search can help.

Or maybe you just need a more detailed book.

But no one here is a lawyer. If you're really looking for solid legal advice, don't come to a software development forum.

Answer 2

BSD license basically allows you unlimited redistribution for any purpose.
Conditions:

1. Provide copyright notice on the original library.
2. You must NOT use the original library name, its authors name etc to promote your product.

The 2nd is pretty obvious, I think.
The 1st one technically can be achieved different ways:

1. by putting copyright in the source file
2. by putting the copyright in the License.txt
   etc

You MUST specify somewhere that XYZ is part of library ABC. It should not necessarily be the header of source code file.

For example this notice should be sufficient if you took class XYZ from ABC and modified it.
Copyright by YOU, under YOUR License. Credits to John Doe for the original code of ZYX from library ABC (see http://link.to.ABC.com).