These Rules are as close as possible to the published version [see P.M. Giles, Jr. Pure Appl. Chem., 1999, 71, 587-643. Copyright IUPAC; reproduced with the permission of IUPAC]. If you need to cite these rules please quote this reference as their source. In the World Wide Web version errors which have been detected have been corrected and in 2004 a list of corrections and other changes was published in Pure Appl. Chem., 2004, 76, 1283-1292. These errors and changes are marked by; which is a link to details of the change and where it applies. Many of these errors were detected during the translation of it into German by K.-H. Hellwich. Additional corrections since this list was published are marked by.