DAU - 1.) The review and approval of capability requirement documents by a designated validation authority.

2.) The process by which the contractor (or as otherwise directed by the DoD Component procuring activity) tests a publication/technical manual for technical accuracy and adequacy.

3.) The process of evaluating a system or software component during, or at the end of, the development process to determine whether it satisfies specified requirements.

Action Engineering - The process of determining the degree to which a model is an accurate representation of the real-world from the perspective of the intended uses of the model.

Example of the difference between Verify and Validate:

- You verify that the 3D design data is authored per company guidelines

- You validate that any derivative 3D data has translated properly (such as a STEP file)