UMLR — What is a DurationInterval

What is the "range" between two durations. Is it a statistical property? is it max to max, min to min, ....?? Ah. I get it. This is a spectacularly confusing class name. Introducing an alternate editorial term compounds rather than mitigates the problem. Use "distance" in the descriptions, then users might grasp that it is not a time interval. In max/min refer to larger/smaller duration rather than range.
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Discussion
Source: Edward Willink
I'm stll very confused, if two duration are being compared in some way, such that the min and max of the range is being found, then the durations must either be duration constants, or offset from some observation. If the two durations do not use the same observation, then there should be no duration interval?