Openings
Openings can be inserted into walls and ceilings. When they are being inserted into ceilings, it should be noted that these elements are by default invisible and must be set as visible before inserting an opening. An attempt to insert an opening in an invisible or non-existent ceiling will, depending on the input tool, either be ignored or a message is displayed indicating that there is no appropriate object at this position into which the opening can be inserted.
Openings can be created freely 
or entered using rectangles 
, circles 
or polygons 
. On free input, the opening is defined in the ‘Properties’ dialog, which is opened over the ‘Properties’ entry in the context menu activated with the a right mouse click – in this way changes to the opening can also be made during input.
The other types of input are used for walls in cross-sections and views, and for ceiling openings in 2D plan views. In this case the ‘Properties’ dialog is not available on input, since the dimensions, sill height and contour are already determined by the choice of input tool.