How does yahoo backlink page rank?

When we check backlinks yahoo siteexpolore, it give us blacklinks with some order, what are they based on? link age or authority or relevant or just random？

according to my experience, high PR backlinks often goes first, of course there r exceptions...and age & relevance...maybe sth to do with it also. New links goes first? i don't know exactly . Probabally, the result based on all the things u mentioned... I'm speaking nothing, lol