Let's say we have a capital H with glyph level PS hints defined as on the image below. The question is how these hints communicate with the rasterizer in order to accomplish gridfitting.
In other words, we have H scaled down to the lower resolution, which looks wrong because of rounding errors (left stem is i.e. one-pixel size and the right is two, the bar is at the wrong position). And then PS autohint approaches rasterizer and says what?
Also, in that conversation, what means the hint position (bold green line) and what hint size?