This Technical Report is a compilation of DSS1 codepoints that are defined for use by ISDN supplementary services. No new information is contained herein since every DSS1 codepoint that is mentioned in this report has already been published in one or more American National Standards. Rather@ this is a comprehensive listing of codepoints for ISDN supplementary services for the reference of developers and other standards committees. Information contained herein is subject to change without notice since the development of new and revised American National Standards on ISDN supplementary services is an on-going activity. The information presented in this Technical Report includes modifications and extensions to DSS1 Layer 3 messages@ information elements@ codepoints and timers defined for ISDN supplementary services that have been published as American National Standards. Codepoints for basic call control (as presented in T1.607-2000) and generic supplementary services procedures (as presented in T1.610-1998) are not contained in this Technical Report. If there are any discrepancies in information between this Technical Report and an American National Standard on an ISDN supplementary service@ then the American National Standard shall take precedence.