What does it mean to graft or flatten?

"Graft" and  "Flatten" changes the data structure inside a parameter. Sometimes it is necessary to modify the data structure because the default layout does not result in the desired operations. Imagine you divide 5 closed curves into 10 segments each. The result of this operation is a data structure of 5 lists with 10 items (points) each. If you were to Flatten this structure, you'd end up with a single list containing 50 items. If you were to Graft this structure, you'd end up with 50 lists of one item each.

For more information on grafting and flatteening, see see the Generative Algorythms book, chapter 5_6_On Data Trees for more information.

~David Rutten