HTML5 longdesc tag for images

I've been reading开发者_高级运维 this webpage http://www.456bereastreet.com/archive/201008/no_longdesc_attribute_in_html5/ anyway I was afraid I may be missing something out so anyway my question is we would be considered "done" if we declare an alt for images and there's nothing else we would have to do to make it "right" right?

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The specification is still in flux. longdesc is still being debated. It may or may not appear.

For HTML 4 and XHTML 1 documents, it would depend on the image and the context in which it appears.