As there are multiple versions of the working principle, they have been organised as such:

  1. Old versions have an additional (Archived)
  2. Versions are labelled in ascending order, ie V3 is more recent than V2.

The current version (V2) can be accessed here.

The archived versions can be accessed using the following links:

Version 1 

All versions can also be accessed via the dropdown menu on the top of the page.