�1����
Introduction
�2����
Reference configuration at the user-network interface
������� 2.1���� Functional groups and reference points
������� 2.2���� Examples of physical realizations
������� 2.3���� Basic characteristics of the interfaces at TB and SB reference
points
������� 2.4���� Relationship between ISDN interfaces
������� 2.5���� Application of B-ISDN model to functional groups
�3����
Physical layer information flows and interface functions
������� 3.1���� Relation with other sublayers or entities
������� 3.2���� Modes of operation
������� 3.3���� Interface function
�4����
UNI related OAM functions
Annex� A � Alphabetical list of
abbreviations used in this Recommendation