PIs in DTD

As I see, the XML 1.0 and XML 1.1 standards allow Processing
Instructions and Comments within DTD declaration. However, the Node type
in DOM, that DTD translated to, does not have child nodes. So , the
question is: how should such (i.e. appearing within DTD) Processing
instruction and Comment nodes be passed to main application (i.e. where
nodes for them should appear in DOM representation for given Document) ?