A new hierarchy for complex plane curves

Abstract: We define the type of a plane curve as the initial degree of the corresponding Bourbaki ideal. Then we show that this invariant behaves well with respect to the union of curves. The curves of type $0$ are precisely the free curves and the curves of type $1$ are the plus-one generated curves. In this note we show first that line arrangements and conic-line arrangements can have all the theoretically possible types. In the second part we study the properties of the curves of type $2$ and construct families of line arrangements and conic-line arrangements of this type.