Android does each Layout element require an XLMNS definition?

I guess this is more of a best practice question. But does each Layout element (LinearLayout, ReleativeLayout, etc.) need a xmlns:android tag? I know the root tag requires it, but should child Layout elements have开发者_开发知识库 it as well?

Thanks.

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no, there's no need to add xmlns to child elements, unless they require attributes unknown to the sdk (for example, the AdMob SDK)