AH, just found the correct terms in google and have found this language which sounds about right:
I hereby grant to Leonardo, its sponsor (The International Society for the Arts, Science and Technology – Leonardo/ISAST), and its publisher (The MIT Press) nonexclusive worldwide rights to reproduce the above-mentioned Illustration in this and all future editions of the above- cited Article in a Leonardo publication. I understand that this permission includes reproduction in any and all media now known or hereafter discovered, including but not limited to print, electronic on-line databases and the World Wide Web. This also includes licensing the Article for document delivery.
I certify that I am the copyright holder of the above-mentioned Illustration. I understand that (1) I will retain copyright to the above Illustration, and (2) my copyright will be prominently displayed next to any reproduction of the above artwork along with any credit line included above. I agree to indemnify Leonardo/ISAST and the MIT Press against any claim or action alleging facts which, if true, constitute a breach of any of the foregoing warranties.