Basically, there are levels for marking which span a number of marks. If you are, when they remark it, within the same level then you do not gain any marks because the marking is deemed "correct" even if you were remarked to have a few more marks. If, however, you are remarked on a higher level then you gain the marks. This is deemed an "genuine marking error and unreasonable marking" because it was marked at the wrong level. I hope this is correct, this is how it was explained to me though, so no guarantees as I haven't actually researched it myself. Hope it helps never the less