Action Subject
                                            Description: Element in the message
                                            Syntax: (header / body).Action Subject name [.header-index ] * [.( sub-element / sub-element-param )]
                                            Examples:
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    header.contact.header-param.expires | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    header.to.uri-param.user-param | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    body.application/dtmf-relay | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Description: Name of the message's element - "/" only used for body types | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Syntax: 1 * ( token / "/" ) | 
                                                
                                            
                                            
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    application/dtmf-relay (body's name) | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Description: Header's index in the list of headers | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Examples: If five Via headers arrive: | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    0 (default)    refers to first Via header in message | 
                                                
                                            
                                            
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Description: Header's element | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Syntax: sub-element-name | 
                                                
                                            
                                            
                                            
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Description: Header's element | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Syntax: sub-element-name [.sub-element-param-name ] | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    header.from.param.expires | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Description: Header's parameter name - relevant only to parameter sub-elements | 
                                                
                                            
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    expires (contact's header's param) | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    duration (retry-after header's param) | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    unknown-param (any unknown param can be added/removed from the header) | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Description: Params can be as values for match and action | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Syntax: param.param-sub-element.param-dir-element.(call-param-entity / ipg-param-entity) | 
                                                
                                            
                                            
                                            
                                            
                                            
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Description: Determines whether the param being accessed is a call or an IP Group | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    call: relates to source or destination URI for the call | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    ipg: relates to source or destination IP Group | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Description: Direction relating to the classification | 
                                                
                                            
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    ds: refers to destination | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Description: Parameters that can be accessed on the call | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    user: refers to username in request-URI for call | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Description: Name of the parameter | 
                                                
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    user: refers to Contact user in IP Group | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    host: refers to Group Name in IP Group table | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    type: refers to Type field in IP Group table | 
                                                
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    id: refers to IP Group ID (used to identify source or destination IP Group) | 
                                                
                                            
                                            
                                            
                                            
                                                
                                                
                                                
                                                
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                                                    Syntax: string enclosed in single apostrophe |