Unclear documentation for min, maxDuration for traces

[kevinburkesegment]

A trace is a collection of multiple spans. What does it mean to pass maxDuration or minDuration to the /api/traces endpoint? The documentation says:

minDuration: Ex. 100000 (for 100ms). Only return traces whose Span.duration is greater than or equal to minDuration microseconds.

maxDuration: Only return traces whose Span.duration is less than or equal to maxDuration microseconds. Only valid with minDuration.

Must all spans in a trace be larger than minDuration, if set? Must only one span in a trace fit within the min and max duration parameters? It's not really obvious what the intention is here.