What are the rules behind 'path' ID generation?

I was trying to map sentences from the current release to an older release (really old, Nov 2017) and I don’t see a clear connection between the previous ‘filename’ and current ‘path’ attributes in the downloads. Two questions here:

  1. Is there some other ID for each utt or is ‘path’ also the unique ID for each utt? If there is another ID, where do I find it?

  2. Is that ID guaranteed to remain the same between future releases?