There are two of them:

- Inter: the two arguments must be lists with two elements (there can be more elements, but only the two first will be handled), that will be interpreted as two straight lines [defined by two points], the operation determine and returns the intersection point. When the two lines are parallel, the result is Nil.
- InterL: the two arguments must be lists with at least two elements, then interpreted as two polylines, the InterL operation determine and returns the points list that intersects the two lines. The intersection’s points are sorted following the same way (direction) as the first argument (and if several points are on the same segment, then they are sorted following the direction of travel of the second argument).