•A crop must not be a Skeleton Crop- these are not designed to create offcuts, but instead to break Offcuts up. The exception is that defines offcut has been enabled in the skeleton crop properties.
•The trunk line of the crop must extend across the plate across the nesting direction. For example if we are nesting right-to-left or left-to-right, the crop must run from the bottom edge of the plate to the top edge of the plate.
This crop is invalid (and in fact I'm not sure how it was drawn, its probably a skeleton crop as well!):
Invalid Cropline
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Valid Cropline, Offcut defined
•Only one or two main crops can be added. If there are two, one is called the "Undercrop", and must be a Wrap Crop.
See also
Defining Offcuts with Crop Lines
Crop Editing: Moving Crop Nodes
Crop Editing: Splitting Offcuts using Tee Handles