Looks a bit funny to write diagnostics and prognostics that way. It highlights the important gnostics root that means superior knowledge. If all you are getting from some dongle attached to the diagnostic port or any other handheld tool or computer program, is a number, then you are not getting full value. Fleets need to know what to do about a code. They need a lot more than a number, an arcane description, or even an extended English description.
That's why fleet management systems and the vehicle OEM systems are involved. There are hundreds of codes that are useful for the product design engineers to understand how to improve the next product. Fleets only need to know what they can do to keep the freight moving without damaging part of the vehicle.
So, when evaluating options for fleet and vehicle management, take an interest in what they offer for diagnostics (after the failure) and if they have any capability for prognostics (before the failure). Don't be agnostic about the subject.