This feature has to option that if one enables the partial credit, a portion of the total points for a question is awarded when an answer isn't entirely correct. This is not the same for Points deducted for incorrect answer as this for all the questions that are wrong. This is when there are certain answers that might be correct.
For example, one could add a multiple choice question:
What is furthers planet from the sun
The correct answer is Neptune which counts 5 marks
For Pluto which is not anymore classified as a planet one can get a partial credit of 40% or 2 marks.
This would apply for:
Fill in the Blank
Hot spot (is already here, but I struggle to get it working)
True False (although this may also be done by Points deducted for incorrect answer)
Thank you for your effort in this matter.