Two distinct DITA document types that are taken from different tools or environments might be functionally equivalent.
A DITA document type is defined by the following:
@domains
attribute on the root
element of the document@class
attributes of all the elements in the
documentTwo document-type shells define the same DITA document type if they integrate identical vocabulary modules, constraint modules, and rules for topic nesting. For example, a document type shell that is an unmodified copy of the OASIS-provided document-type shell for topic defines the same DITA document type as the original document-type shell. However, the new document-type shell has the following differences: