Working with xml instances with different schemas

[Paolo]

Hi all.
I'm working on a translator from DTD to and from XMLSchema.
The schema part (.dtd and .xsd) is working quite well, but I've some
doubt with the instances (.xml).
After I've translated the schema from DTD to XMLSchema, what I should
change in the instance file? If I work with quite simple schemas and
instances, what I've to change more than:
-------------
<!DOCTYPE cust:Customer SYSTEM "...schema.dtd">
-------------
in:
-------------
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:xmlns:....schema.xsd"
-------------
?

Thanks Very Much for your comments and suggestions
P.