> A second point: is it a safe practice to validate a page without carefully reviewing its transclusion into ns0?
Definitively yes.
When can a transclusion can go wrong? In all cases I can think of, the problem come from templates, css classes or general stuff like that. It should be fixed generally and it shouldn't block the page validation since it have nothing to do the the page itself (but maybe I'm missing an obvious example here).
> Alex
Cdlt, ~nicolas