How does scrolling the url query from the Tumblr panel work?

I know I can skip the Dashboard posts by doing something like this:

https://www.tumblr.com/dashboard/X/Y

Where:

  • X> 1 (does not seem to change the offset)
  • 8 <length (Y) <12

I want to know how far I go, but I do not know what X and Y are.