Oops knows that there is a very big amount of regular chess positions. Regular chess positions are those, which can be reached by making regular (allowed) moves. There are about 10 to the power of 120 positions! They are difficult to count, because you need a lot of time to do it. If you count 1 position in 1 second even the age of the universe of about 12 to 15 Billion years wouldn´t be enough to count them all!
Some positions have to be excluded, like the following:
A not regular position: Probably of type [=/=)
But it does not change things fundamentally.