INAThis paper describesen augmentationti the spline conceptto accountfor topologicalrelations between different spline curves. Theee topological relations include incidence relationa,constrainingthe extremesof spline curves tQother spline curves, and also more generalgeometric relations,for example, involving the tangents of spline curves in their extremes.To maintain these incidencerelations,some spline curves may have to be transformed(translated,rotated, scaled),or even deformed(i.e., the shapeof the curve may change)as a resultof modifyingother spline curves.A data structureand algorithmsare given to implementthe propagationof these transformationsand deformations.Based on the augmentedspline concept, to be called stkky splines, both a script system to represent spline structures and an interactive system for editing drawings while automatically maintaining their topological structure are presented.