Cameron said that his renegotiation will be lodged with the United Nations as a legally binding treaty.
If it is agreed, it will be agreed as a legally binding treaty deposited at the United NationsBut Schultz has dismissed that fantasy, confirming that there will be no treaty change and that it won't become legally binding until MEPs have amended it and voted on it after the referendum.
Cameron has form for inventing treaties. You may recall that in the back end of 2011 we were told that he had vetoed a new EU treaty but after submitting a Freedom of Information request for a copy of the draft treaty, the Foreign & Commonwealth Office replied "no EU Treaty was drafted at the European Council in December".