Document History File is more useful than a Tech File in terms of traceability. Document History File is a living document, it contains any mistakes or scrapped information that were made along the process of designing the device. A Tech File only contains snapshots of the final design, it does not explain the thought process which people went through to come up with their final decision. A DHF shows the inputs compared to the outputs while s Tech File does not. Design Controls can be found within the DMR of a DHF but a Tech File does not contain indexes. The time frame that a Doc History File covers is the development leading to the release and after transfer while a Tech File shows information after the transfer. A Tech File is reviewed by a notified body while a DHF is reviewed by the FDA. Maintaining a doc history file is a law based on the compilation of records. It contains all the information needed and more in terms of design when compared to a Tech File.