For Section Maker to correctly evaluate the section properties of the shapes drawn in the Shape Window it is necessary for the geometry of the shape to satisfy the following criteria.

1) A shape cannot be hidden by another shape that is drawn in front of it. If a shape is obscured it will be flagged as invalid and ignored when computing the properties of the section drawn in the Shape window.

2) A shape can only intersect one other shape. Further, one of these shapes must contain the other.

When the shapes drawn in the Shape Window do not meet the above criteria, the values of the section properties displayed in the Property Window will be displayed in red. Furthermore, any individual shapes that are identified as failing the criteria will be shown in red in the Sections table in the Data Window.

Further information about why the section drawn in the Shape Window is invalid can be determined using the Validate command. To validate a shape

§    Choose Validate from the Shape menu

If the section is invalid, one or more messages will be displayed to the user that identify the invalid geometry within the section. Furthermore, if any invalid shapes are detected, the selection in the Shape Window will be cleared and the invalid shapes will be selected.

In general it is only necessary to use the Validate command if the section properties in the Properties Window are displayed in red.