Gradebook

Using the gradebook, I experience difficulties with 'not attested' students. Here is a simple example.

Module 1 category  -          15 of 40 pts.
Module 1 exam category  -  10 of 10 pts.
Module 2 category -            40 of 40 pts.
Module 2 exam category -   1 of 10 pts.
----------------------------
Total   - 66  pts. of  100

Passing grade treshold is 60%.  Mathematically, a student has satisfactory total = 66%, but indeed he is 'not attested' because he/she failed on Module 1 and Module 2 exam. (The term is taken from Russian, you may know better one).

I want be able to mark any activity as obligatory and label students who did not pass it in time with "Not attested" remark.

It can be another column of checkboxes in "Set Categories" tab.
Each checkbox will mean "Obligatory" , or "Passing is required" to a corresponding activity. Students are "not attested" until they get satisfactory grades for every checked item.

Obvously, only elapsed-time activites should be taken into account in algorithm. For example, only when quiz is closed those who failed (or even didn't attempt it) should be treated as  "NA".

I cannot implement this code myself, so I ask community for help and opinions.