When I move the order of a requirement within a feature and then I need to view the history of that change (with History button on the requirement), I can see the position change within what seems to be a technical rank ID (see attachment).
The numbers are relative and don't necessarily reflect the actual number of the requirement. Unfortunately at the moment there is no way to display a more user-friendly value for the requirement rank.
We recently shipped the ability to view Requirement rank through the list views.
A potential workaround would be to create snapshots of these rankings over time to see how this might change over time.
However, at this time, we are unlikely to make updates in this specific area based on community feedback and current priorities. We hope you can understand.