Problem in Saving XML file with DTD

[Shay]

Hello,   I built a simple application that parses an XML document (using JAXP1.2), modifies it using DOM and saves the changes. After this process is completed the file includes everything but the DTD.   I should mention that I'm using the Transformator in order to write the DOM document to a file, but it seems to skip the DTD section when writing the new updated XML file.   Why is it happening and how can I keep the DTD??   Thanks   Shay.