TTML attributes in "no namespace"

According to the TTML XSD the following attributes are in "no namespace"

- region
- style
- begin
- end
- dur
- timeContainer

My question is if this was designed on purpose and if so what the 
intention was. In the spec there is no information on attributes in "no 
namespace".

Best regards,

Andreas

-- 
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Andreas Tai
Production Systems Television IRT - Institut fuer Rundfunktechnik GmbH
R&D Institute of ARD, ZDF, DRadio, ORF and SRG/SSR
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Phone: +49 89 32399-389 | Fax: +49 89 32399-200
http: www.irt.de | Email: tai@irt.de
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Received on Thursday, 26 April 2012 15:21:45 UTC