(1) A spatial access method that defines hyperplanes, in addition to the orthogonal dimensions, which node boundaries may parallel. Space is split by hierarchically nested polytopes (multidimensional boxes with nonrectangular sides). The R-tree is a special case that has no additional hyperplanes. (2) A spatial access method that splits space by hierarchically nested polytopes. The R-tree is a special case in which all polytopes are boxes.