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Priority claimed from GB878720390Aexternal-prioritypatent/GB8720390D0/en
Priority claimed from GB878724790Aexternal-prioritypatent/GB8724790D0/en
Application filed by British TelecommfiledCriticalBritish Telecomm
Priority claimed from EP88307981Aexternal-prioritypatent/EP0306250B1/de
Application grantedgrantedCritical
Publication of ATE98415T1publicationCriticalpatent/ATE98415T1/de