6.2.4. Error Reporting and ResynchronizationThe error reporting service is based on two primitives. S-U-EXCEPTION is issuedby a service user to report an error condition to the other user. Error conditionsdetected by the service provider are reported to service users using the S-P-EXCEPTION primitive. All data in transit is lost as a consequence. Also, unless theerror is handled by the service users, no further activity is permitted. Depending onthe nature of the error, it may be handled in a number of ways: issuing an S-U-ABORT, S-ACTIVITY-INTERRUPT, S-ACTIVITY-DISCARD, orresynchronizing.Resynchronization is a service used for recovering from errors as well as forresolving disagreements between service users. It allows the service users to agreeon a synchronization point, and start from that point. All data in transit is lost as aresult. This service is supported by the S-RESYNCHRONIZE primitive, which maybe issued by either user and requires confirmation. It takes four parameters: type(explained below), serial number (for a synchronization point), tokens (fordistribution of tokens after resynchronization), and user data (an unlimited block).The type parameter may be one of: