UN delegates drafting a treaty to protect the rights of the world's 600 million disabled have resolved many of their differences and are on track to complete the document in August, the diplomat leading the negotiations has said. ''It should be possible to conclude drafting at our next meeting in August,'' New Zealand Ambassador Don MacKay told a news conference after a three-week drafting session. ''We have made real progress and there are relatively few unresolved issues,'' he said. ''But it is more than just dotting the i's and crossing the t's.'' A UN committee that includes all 191 UN member-nations has been working since 2001 on a treaty to promote and protect the rights of the disabled.