The googlecode-tags directory in this revision contains complete copies of CQEngine source code for each of the CQEngine releases which were made while CQEngine was hosted in Subversion on Google Code: versions <=2.1.0, released prior to September 2015.
CQEngine versions >2.1.0 (since September 2015), will be released from GitHub, and tags for those versions can be found directly in the GitHub repository.
This project was previously hosted at: https://code.google.com/p/cqengine/