1     Scope 
        1.1     Application of this Recommendation           
        1.2     Transport network layers   
        1.3     Allocation of end-to-end performance        
 2     References 
 3     Abbreviations   
 4     Terms and Definitions      
 5     Measurement of the block
        5.1     In-service monitoring         
        5.2     Out-of-service measurements         
 6     Performance monitoring at the near end and far end of a path        
 7     Relationship between path performance monitoring and the block-based parameters         
        7.1     General  
        7.2     Estimation of the performance parameters  
        7.3     Estimation of performance events at the far end of a path    
 8     Error performance objectives       
        8.1     End-to-end objectives       
        8.2     Hypothetical reference optical path 
        8.3     Allocation of end-to-end performance objectives    
Annex A – Criteria for entry to and exit from the unavailable state    
        A.1     Criteria for a single direction          
        A.2     Criterion for a bidirectional path    
        A.3     Criterion for a unidirectional path   
        A.4     Consequences on error performance measurements           
Appendix I – Flow chart illustrating the recognition of anomalies, defects, errored blocks, and SES    
Appendix II – Example of OTN layer network trails