-1 == only itself; the null selector, 0 == tree, 1 == childNodes, 2 == childAfter, 3 == youngerSibling, 4 == parentOf
See Implementation
-1 == only itself; the null selector, 0 == tree, 1 == childNodes, 2 == childAfter, 3 == youngerSibling, 4 == parentOf