virtual-sq1 uses (almost*) the same position notation as Jaap's Square-1 optimiser.
The diagram above shows a solved Square-1 with an alphanumeric symbol on each piece. These symbols will represent the pieces they are on.
The position state of a Square-1 is read starting from the top layer (on the left side of the diagram), from just clockwise of the slice, and with the small red side of the equator in front (at the bottom of the diagram). Once you are done with the top layer, move on to the bottom layer, continuing from just clockwise of the slice.
For example, this state in the diagram above is read as:
- Top Layer: A1B2C3D4
- Bottom Layer: 5E6F7G8H
The equator is represented by a "-" if solved (not flipped) and a "/" if unsolved (flipped).
So the complete state of the Square-1 in the diagram above is A1B2C3D4-5E6F7G8H.
* The only difference between the two styles is that virtual-sq1's notation has the equator's symbol between the two layers' states, whereas Jaap's Square-1 optimiser has the equator's symbol after the layers' states. I opted to make this small change so it would be easier to distinguish between the top and bottom layers.