This file is part of the MMIXware package (c) Donald E Knuth 1999 This file may be freely copied and distributed, provided that no changes whatsoever are made. All users are asked to help keep the MMIXware files consistent and ``uncorrupted,'' identical everywhere in the world. Changes are permissible only if the modified file is given a new name, different from the names of existing files in the MMIXware package, and only if the modified file is clearly identified as not being part of that package. (The CWEB system has a ``change file'' facility by which users can easily make minor alterations without modifying the master source files in any way. Everybody is supposed to use change files instead of changing the files.) The author has tried his best to produce correct and useful programs, in order to help promote computer science research, but no warranty of any kind should be assumed.