The anatomical data describing 152 families of Angiosperms constituting the CSIRO famil key for the identification of hardwoods using the microscope has been computerised. A description of 99 anatomical and other features used in this previously unpublished key is presented. Criteria used int he application of features for species identification, together with their variability and difficulties which may arise, are described and illustrated. An outline of the historical development of the edge-punched family key and its transfer to a microcomputer data management system is discussed.