Score
A score is what a tool posts to a line item for a particular user through Assignment and Grade Services.
It carries more than a number. activityProgress says how far the learner has got, and gradingProgress says how far the tool has got with marking it, so a tool can report that someone has submitted before a mark exists. The numeric grade itself is optional.
Treat a score as final only when grading progress says it is fully graded.
