XML : XML inside XML how to use in Base X

I have a project that is to analyse XML documents with the software Base X

My problem is that my XML file is like the model:

  <?xml version="1.0" encoding="UTF-8"?>  <!DOCTYPE us-patent-grant SYSTEM "us-patent-grant-v45-2014-04-03.dtd" [ ]>  ...  <?xml version="1.0" encoding="UTF-8"?>  <!DOCTYPE us-patent-grant SYSTEM "us-patent-grant-v45-2014-04-03.dtd" [ ]>  ...  <?xml version="1.0" encoding="UTF-8"?>  <!DOCTYPE us-patent-grant SYSTEM "us-patent-grant-v45-2014-04-03.dtd" [ ]>  ...    

in other words, it's lots of XML inside this one XML, and when I try to open it with Base X, I get the error:

O destino da instrução de processamento correspondente "[xX][mM][lL]" não é permitido., roughly translating to english is the above

  The instruction destiny of processing "[xX][mM][lL]" isn't allowed.    

how to?