Knowledge Forum 4.5
Knowledge Forum 4.5 was a significant refinement of Knowledge Forum 4.0, with a much richer web interface, although still constrained by the need to support Netscape 4.x-era web browsers.
New features included support for upload and download of files as attachments to views and notes, headings within views, full text and attribute-based searches, and notification by email. It also supported graphs of useful metrics, implemented across platforms using ZDC_ZooLib.
On the back end, a significant change was moving from the original blockstore implementation to one based on B+Trees that uses a neat upward propagting copy-on-write of nodes to make it virtually bullet-proof - only a physical failure of the backing store can cause data loss.