Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA893261A
Inventor
A. T. Knox Keith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Post Office
Original Assignee
Post Office
Publication date
Application grantedgrantedCritical
Publication of CA893261ApublicationCriticalpatent/CA893261A/en