Harvey was able to take the raw data given him by Hyland and convert it (using a Fortran program he wrote himself) into a format that could be used to create a key using the then standard 80-column punched cards.
As well as planning for a computer version of the key, more species were added to the database as well as flower, fruit and seedling features and x-ray images of the leaves.
[6][4] This was a massive undertaking and Edition 3 was not completed until 1992, and released in November 1993[4] It was published on CD-ROMs, covered 1056 taxa, and was available for the public to buy and use on Windows and Mac computers.
[6][9][10] The next milestone in its development was Edition 6 (published 2010), which was transferred to the Lucid softwarea platform and released online for the first time, enabling free access to RFK for any interested person.
[6] Edition 8 (published 2020) represents another significant technological step forward, being available as a mobile app for iOS and Android devices,[1][6] as well as the online version.