How to get BPM version tag used via REST call for Case Instance

Hello, I have read through your API docs. Specifically, these. https://docs.camunda.org/manual/7.8/reference/rest/case-instance/

I am wondering, within a given case instance and a specific BPM process within that case instance having executed, how can I pull the DMN rule that was matched for that execution?

So if a Case instance was generated at 9-1-2020 3:00 PM, and a dmn decision was made as part of a subprocess, and case id is: 1234, how can I see the specific rule that matched for that version of the DMN?

Would appreciate any clarity you could offer.