I think once it has intervened there is 2 thresholds not 1.

So if it falls below the lowest threshold for all 8 days, the line is reverted.

If it stays in between the 2 thresholds, the DLM setting sticks.

If it goes above the 2nd threshold (2880?) DLM is increased further.

The way it was explained to me, was that the caution counters (i.e. days since a profile change) and the barriers are designed to prevent repeated intervention and also making a change which could cause a line to become unstable. But thinking about it, I imagine on a bad line that DLM can keep intervening to provide stability.

I think you're right if the ES value goes over 2880 again. DLM will intervene again. If a positive change was made, then either (for one bad day) the barrier will be reset and the counter continues or DLM intervenes again.

I think the thresholds are always the same.

So if a positive change is made and then the same day the line errors a lot, then DLM will intervene and the next day the profile reduced/interleaving applied. The barrier would be increased in order for there to be stability before DLM makes its next positive change. This is the example used in Plusnet's explanation (line is flapping between good/bad) - http://community.plus.net/library/browsing/fttc-dlm-...