Arrange is a package written in C by Michael Goldwasser of Stanford University for maintaining arrangements of polygons in either the plane or on the sphere. Polygons may be degenerate, and hence represent arrangements of lines. A randomized incremental construction algorithm is used, and efficient point location on the arrangement supported. Polygons may be inserted but not deleted from the arrangement, and arrangements of several thousand vertices and edges can be constructed in a few seconds. Arrange is available from ftp://flamingo.stanford.edu/pub/wass/arrangement.