>I guess the XQuery Update Facility just wants to be ready for whenever such extensions find their way into W3C recommendations. Yes, that's the argument the WG has used for retaining this clause. However, it's still misphrased: the test in a scripting environment will not be that nodes retain their identity (which is still meaningless and untestable), but that variables in the scripting language always refer to the node in its latest (updated) state.