I am an application developer. I have a question regarding "Document Type

Here is the example:

Let's say you have a DTD-1 and a DTD-2:

I was wondering if you can have a DTD inside another DTD...
What I mean is, can I have a DTD (1) which contains another DTD (2) as an
element and therefore can get all its (2) elements..... to fullfill business
requirements and meet the specifications....