That means a preset is currently loaded in memory but isn't necessarily saved anywhere.  We started prefixing that 0 to things, because when people would click on presets in H9 Control, we needed to make clear that the preset was loaded in memory and hadn't overwritten any of their 99 presets.  (You have to explicitly save something to overwrite it.)  Similarly, if you load an algorithm directly using that function, the preset it loads for that algorithm doesn't overwrite the preset you're on;  it's loaded into memory and needs to be saved if you want to keep it.