IfcCurveMeasureSelect.SegmentLength cannot be a parameter, and parameter is issue in general

It is incorrect use parameter value for segment length - it implicitly assumes that length (param) is linear and length(0)=0, these are not a fact.

Generally, I think using of parameters is a nasty thing, because there are many parametrizations for the same curve, and there are many ways to join them for composed curve (and none of which I know is good), and mapping parameter precision to length precision is wired.

I believe the only parameters have sense for generic curve are natural length and fraction of full length

Start with the IfcCurveMeasureSelect.SegmentLength definition and the issue's discussion of curve parameters. Resolve the intended parameter semantics and document the decision in the IFC4.x specification; the work is done when the parameter model is agreed and the affected specification text is updated.

Written by the indexing model from the issue text.