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Priority claimed from GB08421385Aexternal-prioritypatent/GB2163470A/en
Application filed by Silent Channel Prod LtdfiledCriticalSilent Channel Prod Ltd
Priority claimed from EP85305788Aexternal-prioritypatent/EP0173514B1/en
Application grantedgrantedCritical
Publication of ATE61773T1publicationCriticalpatent/ATE61773T1/en