When the is greater than zero, >0 (positive), the compare symbol is increasing faster than the base symbol -- the compare symbol has positive comparative momentum. Of course, your compare symbol could be flat and your base symbol could be decreasing, but math-wise these scenarios are equivalent and the compare symbol has positive comparative momentum.
When the is less than zero, <0 (negative), the compare symbol has negative comparative momentum. Again, the base symbol could be increasing and the compare symbol could be flat, but math-wise this is the same scenario and the compare symbol has negative comparative momentum.
This comparison tactic was documented and described on YouTube channel "Figuring Out Money" in an interesting study between Bitcoin and Gold prices on a .