[OT] good explaination of namespaces and/or larger tha

I feel like these two issues are related.

I've gotten fairly dangerous with XSL but my ignorance of namespaces means my knowledge can only go so far.  I guess it speaks well for XML and XSL that I've been so productive without having a deeper knowledge of XML.

I understand the basic idea that the prefix is locally unique to a document, and the URI is globally (really globally) unique.  I've seen in books how you can declare a namespace in places besides the top of an XML document, but I don't know why you would want to.  I know that there are lots of mechanisms for manipulating namespaces in XSL but I don't understand why/when to use them.

I'm guessing that I should start with understanding just the XML part, but I don't know where to begin.  I know how to use XML when I need one Document type for one specific purpose.  I don't understand how or when someone would architect a solution that goes beyond that.  For example, I have no idea why I would want to or how to go about desinging a solution with multiple, interdependent document types.  

I know that XML is a powerful tool, but I feel like I'm not making the most of it.

There's so much available out there I was hoping to take advantage of the experienced folks on this list.  Any recommendations on articles, websites, books welcome.

Thanks,
+jeff

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