CONTENTS

 1     Scope 
 2     References 
 3     Definitions  
 4     Abbreviations   
 5     System reference diagram
 6     Signals and modulation     
        6.1     Description of signals         
                  6.1.1     4.3125 kHz signalling family          
                  6.1.2     4 kHz signalling family       
        6.2     Modulation
        6.3     Transmit filter characteristics          
                  6.3.1     4.3125 kHz signalling family          
                  6.3.2     4 kHz signalling family       
 7     Description of messages   
        7.1     CL – Capabilities List        
        7.2     CLR – Capabilities List + Request 
        7.3     MR – Mode Request         
        7.4     MS – Mode Select
        7.5     MP – Mode Proposal        
        7.6     ACK(1) – Acknowledge, Type 1  
        7.7     ACK(2) – Acknowledge, Type 2  
        7.8     NAK-EF – Negative Acknowledge, Errored Frame          
        7.9     NAK-NR – Negative Acknowledge, Not Ready   
       7.10     NAK-NS – Negative Acknowledge, Not Supported        
       7.11     NAK-CD – Negative Acknowledge, Clear Down
       7.12     REQ-MS – Request MS Message
       7.13     REQ-MR – Request MR Message           
       7.14     REQ-CLR – Request CLR Message        
 8     Structure of messages      
        8.1     Format convention 
        8.2     Frame structure     
        8.3     Frame check sequence field           
        8.4     Octet transparency
        8.5     Inter-frame time fill 
 9     Message coding format    
        9.1     General  
        9.2     Coding format for parameters in the I and S fields   
                  9.2.1     Parameter classification     
                  9.2.2     Order of transmission of parameters          
                  9.2.3     Delimiting and parsing of parameter blocks
        9.3     Identification field (I)          
                  9.3.1     Message type       
                  9.3.2     Version number    
                  9.3.3     Vendor ID field    
                  9.3.4     Parameter field     
        9.4     Standard information field (S)         
        9.5     Non-standard information field (NS)          
        9.6    Overall message composition         
10     G.994.1 transactions       
       10.1     Basic transactions 
                  10.1.1     Transaction A     
                  10.1.2     Transaction B     
                  10.1.3     Transaction C     
                  10.1.4     Transaction D     
       10.2     Extended transactions       
                  10.2.1     Transaction A:B  
                  10.2.2     Transaction B:A  
                  10.2.3     Transaction A:C 
                  10.2.4     Transaction B:C  
                  10.2.5     Transaction D:C 
       10.3     Message segmentation      
       10.4     State transition diagrams   
11     Start-up/cleardown procedures   
       11.1     Duplex start-up procedures           
                  11.1.1     HSTU-R initiated start-up procedure      
                  11.1.2     HSTU-C initiated start-up procedure      
       11.2     Half-duplex start-up procedures    
                  11.2.1     HSTU-R initiated start-up procedure      
                  11.2.2     HSTU-C initiated start-up procedure      
       11.3     Cleardown procedure       
12     Error recovery procedures          
Annex A – Support for legacy non-G.994.1 devices    
Annex B – Operation over multiple wire pairs    
Appendix I – G.994.1 sample sessions    
Appendix II – Provider code contact information    
Appendix III – Support for legacy DMT-based devices    
Appendix IV – Procedure for the assignment of additional G.994.1 parameters    
       IV.1     Introduction          
       IV.2     Procedure
Appendix V – Rules for code point Table numbering     
Appendix VI – Bibliography