CONTENTS

�Introduction���� � 
Background���� �� 
�1���� Scope
�2���� References
�3���� Abbreviations
�4���� Definitions
������� 4.1���� Digital connections
������� 4.2���� Error performance events and parameters
����������������� 4.2.1���� Events
����� ������������4.2.2���� Parameters
������� 4.3���� Functions of error performance objectives
�5���� Performance objectives
�6���� Apportionment of overall objectives
������� 6.1���� Basic apportionment principles
������� 6.2���� Apportionment strategy for the errored seconds requirement
������� 6.3���� Apportionment strategy for the severely errored seconds requirement
Annex A � Available and unavailable time
Annex B � Guidelines concerning the interpretation of Table 1
Appendix I
� Inconsistencies between Recommendations G.821 and G.826
������� I.1���� Introduction
������� I.2���� Comparison of the SES definitions and objectives
������� I.3���� Comparison of Errored Second Ratio objectives
������� I.4���� Summary