xmlns format confusion

[TaylorF]

\[code\]<linkbase xsi:schemaLocation="http://www.w3.org/1998/linkbase http://www.xbrl.org/2003/schema.xml" xmlns="http://www.noprefix.org/2003/linkbase" xmlns:xlink="http://www.w3.org/2005/xlink" xmlns:xsi="http://www.w3.org/1999/XMLSchema"> <roleRef roleURI="http://www.greenserve.com/role/Commitgencies" xlink:href="http://stackoverflow.com/questions/12794052/Commitmentsngencies" xlink:type="simple" /> </linkbase>\[/code\]In this xml there is a xmlns attribute without followed by a \[code\]:\[/code\] and a prefix name. \[code\]xmlns="http://www.noprefix.org/2003/linkbase"\[/code\]but others have a colon and prefix after the xmlns. So when I try to parse this xml to get the \[code\]roleref\[/code\] tags with the "descendants" function it doesn't show anything. But if I add a \[code\]:\[/code\] and a prefix after that xmlns then it can parse properly. Why it acts like it can anyone explain? Thanks.