Non-manifold but valid Polysurface

valid_non-manifold.3dm (2.8 MB)

why is a non-manifold Polysurface still considered “vaild” ?
_Check → valid polysurface

i think in 99% a non-manifold Polysurface can be considered as “bad” / “useless”.
so i would expect the _check command to report this.

thx

kind regards - tom