Yo - NewGuy:
You'll get better response if you use your signature to describe your machine and Archicad version. We have people here asking about older software daily who need a different answer.
Friday a bad day for quick response since most users are getting drunk until Sunday after a week of PC software challenges.
You'll want to study "Floor Plan Cut Plane" in the Document Menu since this might lead to the answer. If you are in Archicad 11, that is.
Dwight Atkinson