When we were first building the world we knew that we would end up with a multiverse. Every sci-fi/fantasy world that runs long enough eventually has one and we figured it was best to simply plan and integrate it from the start. While most of these multiverses seem to have rather arbitrary naming conventions, such as Earth 616, Earth 4, Mirror Earth ect, we wanted to give ours a bit more structure. Also, we wanted to look and pay homage to real math and science in our world so we chose to use the designation Earth 6.28, also known in math as Tau.
What is Tau you ask? Most of you are probably familiar with Pi, or 3.14 and using it when working with circles. Such as using 2πr to find the circumference of a circle. Tau is 6.28, or 2π, and can be used to simplify many equations in math and physics. For a simple example to find the surface area of a cylinder you need the radius (r) and the height (h). Plug that into 2πrh+2πr^2 and you have your awner. This could be simplified as τrh+τr^2 just by using the correct circle constant. Every time you have to take a step: add, subtract, multiply ect, it opens up possibilities of errors. The fewer steps you need to take the faster and more accurate you will be. If you want to see more in-depth arguments about the benefits of Tau vs Pi check out the links.