CONTENTS

 1     Scope
 2     References
 3     Terms and definitions
 4     Abbreviations
 5     Performance-significant reference events
        5.1     Recommendation Q.931 (Recommendation I.451)
        5.2     Recommendation Q.921
        5.3     X.25 layer 2 (LAPB)
        5.4     Recommendation Q.764
        5.5     Frame switching
        5.6     Frame relaying
        5.7     Recommendations Q.2931 and Q.2971
        5.8     Recommendation Q.2762
        5.9     B-ISDN ATM layer
       5.10     Unrestricted digital bearer services
                 5.10.1     Performance-significant reference events
                 5.10.2     The relevant bit of user information