x~~~~0~~~~~~~~~0~~~~~x
\ /
\ /
\ /
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0
Sorry, I forgot this case. Yes, that probably happens a lot. Actually my own Isecalc does create this quite frequently.
Speaking of Isecalc, it is also used to create the edge line that marks the intersection between two interpenetrating surfaces. In that case, edge lines are indeed "floating" in the middle of surfaces (but there is no need for smoothing anyway!)
