A simple idea which might get us a long way:

Add two new fields to a course:

• course value (eg credit points)

• course pass grade (value between 0 and 100%)

When the total course grade percentage for a student exceeds the pass grade percentage, then the student is assumed to have passed that unit.

This status can be copied to a new table on a regular basis, so that even after unenrolling the record remains there.

On My Moodle, and also on a new admin report screen, all these values can be displayed to give a course record for that student, with a total of credits.

Simple but should meet the needs of many people.

(Full specs from 2009: http://docs.moodle.org/en/Development:Course_completion)