SVG Schema: URL for XMLSchema.dtd ?

Hi;

in the doctype of the SVG 1.1 Schema, there is
<!DOCTYPE schema SYSTEM "XMLSchema.dtd"
.

Which version if the XMLSchema.dtd is referenced here?
Is there a normative DTD for W3C Schema, or should a Schema be used to 
validate schemas?

Would it make sense to change the doctype of the SVG 1.1 to reference a 
public definition, via http, to resolve all this, so that

<!DOCTYPE svg PUBLIC "[...]"
  "http://www.w3.org/[.xsd or .dtd]">

?

Tobi

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