Sketch selection of broken projected loop

[bcrowell]

I have seen a couple of posts asking about this that were older and am hoping that since something so simple hasn't popped back up maybe it is available and I simply haven't seen it.

Is there a way to not select construction geometry in a sketch- or vice versa (to only select construction geometry)?  It would save me at least an hour just today to have that capability in order to close the loops (that Inventor should have already projected as closed).  That brings me to a second question...

How is it possible to cut through a piece of solid geometry and have a broken loop?  For it to be solid, it has to be a closed profile, so any slice through it should be a closed loop, from any angle, any section, anywhere in the solid.  Anywhere.  Right?  So why am I cutting through a solid part and spending hours redrawing the entire cut loop, only to have to not be able to hide the construction geometry so it doesn't come up when I try to close the loop?

[JDMather]

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@Anonymous wrote:

I have seen a couple of posts asking ....

 That brings me to a second question...

.... so any slice through it should be a closed loop, ...

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I will wager that any posts you found also suggested posting file that exhibited the behavior.

Slice feature can be done with an open profile.

[bcrowell]

I can't usually post my file as most all are proprietary, but I can post this one since it is in no way usable at the moment anyway.  

However.  I understand that slice can be an open profile (if you're cutting through a surface), but how can it be physically possible in the 3D realm for it to slice through a solid (EVER) and not come up with anything but a point, line or a closed loop?  It's like saying that you can have a graph of a function that starts negative and ends positive and saying it never passes through zero.  If you pass through a solid body (which in CAD means it has to be a completely closed body) you should created a closed profile.  

Any time you slice through a solid model and you get a loop you should get a closed loop.