MIT licence copyright notice for derived works

Question

We're thinking of using some open-source MIT-licensed software in one of our web projects (a jQuery datetime plugin).

The first line of the MIT licence is:

Copyright (c) [year] [copyright holders]

If we include the plugin as-is (without making any changes), I understand we need to include the licence with only the original author (though the actual copyright notice at the top of the js file doesn't specify a year):

Copyright (c) 2013 Keith Wood

If we make changes to the plugin, what does the copyright notice become?

Copyright (c) 2013 Keith Wood, 2013 [My name/Company name]

Do you need to include all previous authors or is there another way of handling such a notice?

Answer 1

The license for that plugin doesn't say "Copyright (c) 2013 Keith Wood." It says:

Copyright 2013 jQuery Foundation and other contributors

I would imagine you could simply leave it just like that. If you want to include your company name, you could simply say:

Copyright 2013 jQuery Foundation, [My name/Company name] and other contributors.

The MIT license simply states that existing copyrights must be preserved. In other words, don't remove someone else's copyright notice. This, of course, doesn't preclude you from adding "portions copyrighted by [me]" to the copyright header.