Release 1.x to 6.x Series
In ye olde olden days, back when dinosaurs roamed the internet and before there was color on TV, each new deployable release package would get a new "major" revision number (1.0.0, 2.0.0, etc).
Version 1.x.x was an internal prototype. The story listing for that release is lost to the sands of time.
Version 2.1.0 was released on 2/1/2010 and was focused on some demo use cases.
Version 3.0.0 was released on 2/4/2011 and contained an early production-ready system.
Version 4.0.0 was released on 3/14/2011.
Version 5.0.0 was released on 3/31/2011.
Version 6.0.0 was released on 5/9/2011 and introduced Attendance Upload, application queues, and other core system frameworks.