I think maintaining a DHF is necessary and beneficial from a company or device designer point of view but not for device approval. Every product goes through several iterations, changes and modifications before arriving at the final design. As the product is approved or submitted for approval based on the final model of the design, in favor of the EU regulatory style of philosophy, I think the device design specifications on the final design would be appropriate to make a decision on whether the device meets the requirements or not. Otherwise in an ideal situation, a regulatory body should not need the design history from its ‘first prototype’ to approve the ‘final design’.