Help deciphering someone else's XML schema

Hi,

I'm looking at some XSLT and XSD code from another company.  The second line
of the XML is the following:

<rr:CReport xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:rr="urn:Correlagen:RightReport"
xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet"
xsi:schemaLocation="urn:Correlagen:RightReport">

I'm a little rusty (well, very rusty) with the XML, XSD and XSLT namespaces,
and could use a little help deciphering that line.  

When I take that file and put it into EditiX, and create a Schema (.xsd)
file, I get some errors with validation.  They read:

Invalid 'name' attribute value 'ss:Type': 'The ':' character, hexadecimal
value 0x3A, at position 2 within the name, cannot be included in a name.'. 

file:///usr/local/XSV/xsvlog/tmpbN14RIuploaded:143:7
<file:///usr/local/XSV/xsvlog/tmpbN14RIuploaded:143:7> : Invalid per
cvc-attribute.1.2: attribute type check failed for {None}:name: ss:Type does
not match pattern [^:]*

(two different validators).

So, if someone can point me in the right direction for deciphering the
namespaces and what xsi: means, and why I'm getting some errors with
validators, I'd appreciate it.

Note that these files are created externally, and I can't change them.

Thanks,

Michael Gosselin
Athena Diagnostics, Inc.
(508) 756-2886 x3708
(800) 394-4493 x3708