The Canon FD lens mount is a physical stanard for connecting a photographic lens to a single-lens reflex camera body. The standard was developed by Canon of Japan and was introduced in March 1971 with the Canon F-1 camera. It was the primary Canon SLR lens mounting system until 1987 when the cameras from the Canon EOS series were first produced. The last camera in the FD system was the Canon T60, from 1990. The FD mount replaced Canon's earlier FL mount; FD-mount cameras could use FL lenses in stop-down metering mode. There is no known meaning for 'FD', and Canon has never disclosed what, if anything, it stands for.