View changed fields on a Req?

Summary:

After a Req is submitted to workflow, approvers may Edit the req and then resubmit to workflow.

Need to be able to view the original values from before the approver edited the Req.

Content (please ensure you mask any confidential information):

View Document History shows that changes were made to a Req during workflow, but does not specify what the changes were (what values where changed? what were the original values? what were they changed to?).

How can I find this information? Viewing the Req only shows the current (edited) version. Even viewing the BPM notifications seems to only show the current (edited) version.